Answer:
helium , krypton,xenon,radon, argon are noble gasses
Adrian loves the pancakes! The problem is, the recipe serves only six, and he has 540 people in his family (including aunts, uncles, and cousins). Now, he needs help increasing the recipe to feed his entire family. However, Adrian is particular - he insists on using only three significant figures with scientific notation.
Answer:
ingredient. U.s unit. SI unit. SI unit(540)
flour. 2cups. ²/6. 180cups = 1.8×10²
milk. 2cups. ²/6. 180cups. =1.8×10²
eggs. 2. ²/6. 180eggs. =1.8×10²
melted butter. ⅓cup ¹/18. 30cups. =3×10¹
sugar. 1spoon. ¹/6. 90spoons. =9×10¹
baking powder 2spoons ²/6. 180spoons. =1.8×10²
salt. ½spoon. ¹/12. 45spoons. =4.5×10¹
Explanation:
1) to get the SI unit divide the U.S unit by 6
example:eggs = 2÷6. =²/6
2) to get the SI unit for 540 people ,multiply the SI unit by 540.
example:eggs ²/6×540. = 180
3)convert the answers to scientific notation
example:eggs =180. =1.8×10²
Given isotope of nitrogen (N) contains 7 electrons, 7 protons and 8 neutrons. - What is the mass number - What is its atomic number
Answer:
Mass no= 16
and atomic no= 7
Explanation:
mass number is equals to number of protons + number of neutrons .
atomic number is equals to number of protons .
Suppose you carry out a titration involving 3.00 molar HCl and an unknown concentration of KOH. To bring the reaction to its end point, you add 35.3 milliliters of HCl to 105.0 milliliters of KOH. What is the concentration of the KOH solution?
Answer: The concentration of the KOH solution is 1.01 M
Explanation:
According to neutralization law:
[tex]n_1M_1V_1=n_2M_2V_2[/tex]
where,
[tex]n_1[/tex] = basicity of [tex]HCl[/tex] = 1
[tex]n_2[/tex] = acidity of KOH = 1
[tex]M_1[/tex] = concentration of HCl = 3.00 M
[tex]M_2[/tex] = concentration of KOH = ?
[tex]V_1[/tex] = volume of HCl = 35.3 ml
[tex]V_2[/tex] = volume of KOH = 105.0 ml
Putting the values we get:
[tex]1\times 3.00\times 35.3=1\times M_2\times 105.0[/tex]
[tex]M_2=1.01[/tex]
Thus the concentration of the KOH solution is 1.01 M
What do neurons and protons have in common?
Answer:
Protons and neutrons have almost the same mass and are both located in the nucleus of the atom
Answer:
Protons and neutrons have almost the same mass and are both located in the nucleus of the atom. Protons are charged particles. Neutrons are neutral particles. ... The positive charge of the protons in the nucleus is balanced by the negative charge of the electrons.
A 36.0−g sample of an unknown metal at 99°C was placed in a constant-pressure calorimeter containing 70.0 g of water at 24.0°C. The final temperature of the system was found to be 28.4°C. Calculate the specific heat of the metal. (The heat capacity of the calorimeter is 12.4 J/°C.)
Answer: 0.52849 j /g °C
Explanation:
Given the following :
Mass of metal = 36g
Δ Temperature of metal = (28.4 - 99)°C = - 70.6°C
Mass of water = 70g
Δ in temperature of water = (28.4 - 24.0) = 4.4°C
Heat lost by metal = (heat gained by water + heat gained by calorimeter)
Quantity of heat(q) = mcΔT
Where; m = mass of object ; c = specific heat capacity of object
Heat lost by metal:
- (36 × c × - 70.6) = 2541.6c - - - - (1)
Heta gained by water and calorimeter :
(70 × 4.184 × 4.4) + (12.4 × 4.4) = 1288.672 + 54.56 = 1343.232 - - - - (2)
Equating (1) and (2)
2541.6c = 1343.232
c = 1343.232 / 2541.6
c = 0.52849 j /g °C
Give the word equation for the reaction between hydrogen and oxygen
Answer:
Hydrogen gas (H₂) + Oxygen gas (O₂) → Water (H₂O)
Explanation:
Hydrogen reacts with oxygen to form water. The reactants are hydrogen and oxygen and the product is water.
Answer:
Word Equation:
Hydrogen + Oxygen = Water
Hydrogen gas reacts with Oxygen gas to give Water.
The chemical Reaction is as follows:
[tex]2H_{2} + O_{2}[/tex] => [tex]2H_{2}O[/tex]
If 50.0cm3of a saturated solution of KNO3at 40oC contained 5.05g of the salt. What is the solubility of the salt at 40oC? [KNO3=101].
Answer:
The solubility of KNO₃ at 40° C is 1 mol/dm³
Explanation:
The solubility of a substance is the number of moles of that substance (solute) contained in a unit volume of solvent at that particular temperature.
Now, Solubility = n/V where n = number of moles of KNO₃ and V = volume of saturated solution = 50.0 cm³ = 0.05 dm³
n = m/M where m = mass of KNO₃ = 5.05 g and M = molar mass of KNO₃ = 101 g/mol
n = 5.05 g/101 g/mol = 0.05 mol
Solubility = n/V
= 0.05 mol/0.05 dm³
= 1 mol/dm³
So, the solubility of KNO₃ at 40° C is 1 mol/dm³
write chemical equation for the following decomposition reactions. Aluminum oxide(s) decomposes when electricity is passed through it.
Answer:
2Al2O3 (l) ---> 4Al (l) + 3O2 (g)
Explanation:
The reaction is the electrolysis of aluminium oxide. It decomposes aluminium oxide (Al2O3) into aluminium metal (Al) and Oxygen (O2). In this process, aluminium oxide is molten (liquid state) so that ions can move to complete the electricity circuit.
Al2O3 (l) ---> Al (l) + O2 (g)
Balance the equation:
2Al2O3 (l) ---> 4Al (l) + 3O2 (g)
what is the valency of hydroxide
Answer:
Its valancy is 1.
As it has the formula OH-.
It has valancy 1.
hope it helps..
HELP ME OUT PLZ Today is the deadline
Answer:
Option (1)
Explanation:
When two or more substances are chemically combined in a fixed proportion of mass, substance formed is a compound.
Properties of a compound are different from the properties of the elements from which the compound is formed.
If Magnesium (Mg) is burned in the presence of Oxygen (O₂), Magnesium oxide (MgO) is formed.
Properties of MgO are different from Mg and O₂ because MgO is a COMPOUND.
Option (1) will be the answer.
which one of the following electronic configuration represents the element that forms simple ion with a charge of-3? (a)1s^2,2s^2,2p^6,3s^2,3p^1 (b)1s^2,2s^2,2p^6,3s^2,3p^3 (c)1s^2,2s^2,2p^6,3s^2,3p^6,3d^1,4s^2 (d)1s^2,2s^2,2p^6,3s^2,3p^6
Answer:
(b)
Explanation:
The 3s^2, 3p^6 orbitals form -3 charge.
This is the element phosphorous and an example of a -3 ion is in aluminium phosphide, AlP3.
The electronic configuration which represents the element forming a simple ion having with a charge of -3 is; 1s², 2s², 2p⁶, 3s², 3p³. Option B is correct.
In this electronic configuration, the element has a total of 16 electrons. To form a simple ion with a charge of -3, the element needs to gain three electrons. This is achieved by adding three extra electrons to the existing configuration.
When the element gains three electrons, the electron configuration becomes:
1s², 2s², 2p⁶, 3s², 3p⁶
This configuration represents the stable octet configuration, where the element has a complete outer shell with eight electrons. Since the charge is -3, it means the element has gained three extra electrons to achieve a stable configuration.
Therefore, the correct electronic configuration representing the element that forms a simple ion with a charge of -3 is 1s², 2s², 2p⁶, 3s², 3p³
Hence, B. is the correct option.
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Give two reasons why mixing and heating sulphur powder and iron filings on a watch glass is chemical change
Answer:
When iron filings and sulphur powder are mixed and heated they undergo a chemical reaction and form ferrous sulphide (FeS). It is a new substance which has properties entirely different from Fe and S. Therefore, heating of mixture of iron and sulphur powder is a chemical change.
Two oxides of lead were separately reduced to metallic lead by heating in a current of
i) Mass of yellow oxide taken=3.45g
ii) Mass of brown oxide taken=1.227g
Loss in mass during reduction=16g
Show that the above data illustrate the law of multiple proportions.
Answer:
HeyA ❤
Let us consider the mass of oxygen as 1 g.
Mass of lead obtained from yellow oxide = 3.45 g – 0.24 g = 3.21 g
Mass of oxygen = 0.24 g
The mass of lead that combines with 0.24 g of oxygen = 3.21 g
Therefore, mass of lead that combines with 1 g of oxygen = 3.21/ 0.24 = 13.4 g
Mass of lead obtained from brown oxide = 1.227 g – 0.16 g = 1.067
Mass of oxygen = 0.16g
The mass of lead that combines with 0.16 g of oxygen = 1.067 g
Therefore, mass of lead that combines with 1 g of oxygen = 1.067/ 0.16 = 6.66 g
Now, ratio of masses of lead which combines with a fixed mass of oxygen = 13.4 : 6.66
= 2 :1
Thus, masses of lead which combine with the fixed mass of oxygen are in the ratio of (2:1) i.e. small whole numbers.
Hence, the law of multiple proportions is illustrated.
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Adding a base to a solution would...?
Answer:
it would decrease [h+]
Explanation:
This is due to neutralization If a base is added to an acidic solution, the solution becomes less acidic and its position changes to the middle of the pH scale.
hope this helps
Answer:
Raise the pH
decrease [H+]
Explanation:
=> Adding base would raise the pH (Bases have more pH and Acids have less pH)
=> Adding base would decrease the concentration of [H+] ions as it contains hydroxyl ions which neutralized with H+ ions so as a result the concentration of [H+] ions decreases.
Which of the following is a halogen?
O A. Neon (Ne)
B. Iodine (1)
O C. Oxygen (0)
O D. Potassium (K)
Answer:
[tex]\boxed{\mathrm{Iodine}}[/tex]
Explanation:
Halogens are elements in group 17 or 7 in the periodic table.
Iodine is a halogen.
Therefore, iodine, an Halogen
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4. How much force, in g cm / s2 , is exerted by a golf ball described in problem 2 striking a tree while accelerating at 20 cm / s2 ? Show how you can solve this problem without knowing that F = m a. Explain your solution.
Answer:
Explanation:ifk
If the external vapor pressure is 2.0 atm , what is the vapor pressure of the water at its boiling point?
Answer:
22
Explanation:
22
A 25.0 mL sample of a solution of an unknown compound is titrated with a 0.115 M NaOH solution. The titration curve above was obtained with pH at equivalence point of around 8. The unknown compound is ________.
Answer:
Weak acid
Explanation:
A titration curve is a graphical description of the change in pH of the solution in the conical flask as the reagent is added from the burette. A titration curve can be plotted for the different kinds of acid and base titrations. The volume of the titrant is always plotted as the independent variable and the pH of the solution as the dependent variable. The equivalence point is read off from the titration curve. A titration curve is very important because it shows the pH at various points during the titration.
A weak acid/strong base titration leads to an equivalence point above 7. From the question, we were told that the pH at equivalence point lies around 8. Hence the unknown substance must be a weak acid.
In heating and melting curves, what is the name of the heat associated with the solid-liquid phase? A. Heat of formation B. Heat of fusion C. Heat of sublimation D. Heat of vaporization
Answer:
C I believe not quite sure tho
In heating and melting curves, the name of the heat associated with the solid-liquid phase is Heat of fusion.
What is the Heat of fusion ?
The standard fusion enthalpy is the amount of thermal energy required for a single mole of a substance to change states from a solid to a liquid or vice versa is known as the heat of fusion or specific melting heat. The melting point is the temperature at which it takes place, and it is also known as the latent heat of fusion or the enthalpy change of fusion.The temperature of a liquid or solid goes down when thermal energy is taken away. The temperature rises when heat and energy are added. However, additional energy—the heat of fusion—is required at the melting point—the transition point between solid and liquid. The molecules of a substance need to become more organized in order to change from liquid to solid. They require the withdrawal of additional heat in order to maintain their solid state. In the opposite direction, additional heat is required to induce the disorder from the solid crystal to the liquid.The temperature of water as it freezes can be measured to observe the heat of fusion. When you place a closed container of room temperature water in a very cold environment, say 20 °C, the temperature will gradually fall until it is just below the freezing point. After that, the temperature rises and stays the same as the water crystallizes. The temperature will again fall steadily after it has completely frozen.The heat of fusion causes the temperature to stop falling at (or just below) the freezing point. Before the temperature can continue to fall, the energy from the heat of fusion must be removed—the liquid must transform into a solid.
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A proton travels at a speed of 2.0 × 106 meters/second. Its velocity is at right angles with a magnetic field of strength 5.5 × 10-3 tesla. What is the magnitude of the magnetic force on the proton?
So here we are given that the the velocity of the proton ( V ) is 2.0 × [tex]10^6[/tex] meters / second, with a magnetic field of strength 5.5 × [tex]10^{-3}[/tex] tesla. If they each form a right angle, they are hence perpendicular to one another, such that ....
F = q( V × B ),
F = q v B( sin ∅ ),
F = q v B( sin( 90 ) )
.... they form the following formula. Let's go through each of the variables in our formula here -
{ F = Magnetic Force ( which has to be calculated ), q = charge of proton (has charge of 1.602 × [tex]10^{19}[/tex] coulombs ), B = magnetic field }
All we have to do now is plug and chug,
F = ( 1.602 × [tex]10^{19}[/tex] )( 2.0 × [tex]10^6[/tex] )( 5.5 × [tex]10^{-3}[/tex] ) = ( About ) 1.8 × [tex]10^{-15}[/tex] Newtons
Answer: hey there, the answer to your question is (E)
Explanation:
True or False a. Sodium chloride is the main salt found in sea water. ……………………………………………………………………. b. Potassium bromide salt is not found in sea water ……………………………………………………………………. c. Both evaporation and electric conduction techniques prove that sea water contain the dissolved salts. …………………………………………………………………….. d. The amount of fresh water is greater than 5% of the total Earth water. …………………………………………………………………….. e. In water treatment process, filter membrane is used to remove fine particles and other impurities from water. …………………………………………………………………………....
Answer:
A is true NaCl
B is false K2Br
C is true
D false its only 0.03 percent
E is true
Which of the following elements does not lose an electron easily? NA F MG AL
Answer:
F
EXPLANATION
Among the given elements fluorine(F)can not lose electrons easily because of its high electron affinity, high nuclear charge and high electronegativity.
Answer:
F
Explanation:
it won't lose electron , rather it would gain electron to complete its octate......
Electronic Configuration of F = 2,7
So F will gain 1 electron ....
What is the correct formula for the Ksp of the reaction MgF2(s) – Mg2+ (aq) + 2F (aq)?
Ksp = [Mg2+][F]
Ksp =[Mg2+][F]2
Ksp = 2[Mg2+][F]
Ksp = [Mg2+][F]
Answer:
Ksp = [Mg₂⁺][F⁻]²
Explanation:
Ksp is the equilibrium constant for a solid dissolving in an aqueous solution. The equilibrium constant for a reaction is always products over reactants.
MgF₂ (s) ⇒ Mg₂⁺(aq) + 2F⁻(aq)
The equilibrium constant would be K = [Mg₂⁺][F⁻]². Since MgF₂ is solid, it is not included in the equilibrium expression.
Therefore, Ksp would be the same as the equilibrium constant.
Ksp = [Mg₂⁺][F⁻]²
Hope this helps.
Answer:
Ksp = [Mg2+]3 × [PO43-]2
Explanation:
edge 2021
It's urgent! Any kind soul please help me ASAP!
Answer:
a white precipitate of barium chloride is formed as displacement reaction takes place.
someone plz plz answer this hurry plz it
Answer:
b
Explanation:
30cm^3 of a dilute solution of Ca(OH)2 required 11 cm^3 of 0.06 mol/dm^. Hcl for complete neutralization. Calculate the concentration of the Ca(OH)^2 solution in mol/dm^3 and g/dm^3
Answer: Thus concentration of [tex]Ca(OH)_2[/tex] in [tex]mol/dm^3[/tex] is 0.011 and in [tex]g/dm^3[/tex] is 0.814
Explanation:
To calculate the concentration of [tex]Ca(OH)_2[/tex], we use the equation given by neutralization reaction:
[tex]n_1M_1V_1=n_2M_2V_2[/tex]
where,
[tex]n_1,M_1\text{ and }V_1[/tex] are the n-factor, molarity and volume of acid which is [tex]HCl[/tex]
[tex]n_2,M_2\text{ and }V_2[/tex] are the n-factor, molarity and volume of base which is [tex]Ca(OH)_2[/tex]
We are given:
[tex]n_1=1\\M_1=0.06mol/dm^3\\V_1=11cm^3=0.011dm^3\\n_2=2\\M_2=?\\V_2=30cm^3=0.030dm^3[/tex] [tex]1cm^3=0.001dm^3[/tex]
Putting values in above equation, we get:
[tex]1\times 0.06mol/dm^3\times 0.011dm^3=2\times M_2\times 0.030dm^3\\\\M_2=0.011mol/dm^3[/tex]
The concentration in [tex]g/dm^3[/tex] is [tex]0.011mol/dm^3\times 74g/mol=0.814g/dm^3[/tex]
Thus concentration of [tex]Ca(OH)_2[/tex] is [tex]0.011mol/dm^3[/tex] and [tex]0.814g/dm^3[/tex]
Answer:
d
Explanation:
d
Based on the kinetic molecular theory, which of the following statements is correct about the particles in a sample of gas at a constant temperature and
volume?
They have negligible kinetic energy
They attract each other with strong forces.
There is a lot of empty space between them.
Their net kinetic energy decreases due to collisions.
Answer:
There is a lot of empty space between them.
Explanation:
The kinetic molecular theory postulates that a substance is made up of tiny particles called molecules. The molecules of a gas are in constant random motion and collide elastically with each other. They also collide with the walls of the container.
The magnitude of intermolecular forces of attraction between gas molecules is very small. Hence gas molecules are largely apart with a lot of empty space between gas molecules.
Answer:C, There is a lot of empty space between them.
Explanation:
Answer the following questions:
1. Define a compound. State three points of evidence to show that sodium chloride is a compound.
2. When Iron powder and Sulphur powder were mixed together and heated strongly, a substance A was formed. When did. Hydrochloric acid was added to substance A, the gas B was evolved.
a) What is A and what type of substance is it?
b) Name the gas B. State one characteristic property of gas B.
c)Is the reaction of Iron and Sulphur powder a chemical change or a physical change.
Answer the question according to the class 9th student.
Answer:
1. A compound is a group of elements that cannot be separated by physical methods.
NaCl is a compound becuse it cannot be separated by physical methods.
It consists of postive and negative ions.
It can be separated only by chemical reactions.
2. (a) A is a mixture of iron and sulphur and it is in liq form.
(b) Gas B is hydrogen gas and it has sharp pungent irritating smell.
(c) It is a physical change.
Explanation:
A 35 gram of saturated solution is distilled out completely. If the solubility of the solute is 110, find the amount of residue solute snd distilled water
Answer:
3850g
Explanation:
Solubility is the amount of solute dissolved in a solvent.
Solubility is mass of solute÷mass of solvent
The solvent is 35grams
Solute?
Solubility of solute is 110
110=x/35
= 110 × 35
The amount of residue solute is 3850g
How to know number of proton/electron from ionisation energy?
also how to know ionisation energy from number of electron?
How to know group of element? (like Iodine - group 17)
Answer:
Ionization energy decreases from top to bottom in groups as the size of the atom becomes larger. For example, the first ionization energy of hydrogen is 1310 kJ mol⁻¹. The first ionization energy of lithium is 519 kJ mol⁻¹. Because lithium is a bigger atom and has more protons than hydrogen, its ionization energy is lower. So, in groups, the lower the ionization energy, the larger the atom and the more protons/electrons it has.
Ionization energy also increases from left to right across a period. The more protons in the nucleus, the greater the attraction between the nucleus and the electrons, which makes it more difficult to remove electrons. Helium has an ionization energy of 2370 kJ mol⁻¹ while hydrogen has an ionization energy of 1310 kJ mol⁻¹ because helium's nucleus has 2 protons attracting electrons instead of 1 like hydrogen. So for periods, the higher the ionization energy, the smaller the atom and the more protons/electrons it has.
Ionization energy is the energy required to remove an electron from its orbital around an atom. It increases across a period because the number of protons in the nucleus increases. This creates a stronger attraction between the nucleus and electrons, causing the electrons to be held tighter by the higher nuclear charge. Because the electrons are more difficult to remove, more energy is required which causes the ionization energy to be higher. So for periods, the more electrons the atom has, the higher the ionization energy. Ionization energy decreases down a group because the first electron removed is farther from the nucleus as the number of protons increases. Being farther away from the nucleus makes it easier for the electron to be pulled off as it is more loosely bounded, so less energy is required to remove the electron which causes the ionization energy to be lower. So for groups, the more electrons the atom has, the lower the ionization energy.
Groups are vertical columns going down on the periodic table. If you look at a periodic table, across the top, you will see the numbers 1-18. Those numbers signify the 18 groups of the periodic table. Iodine is a halogen so it is under Group 17 to the far right of the periodic table.
I attached two periodic tables for reference to everything that I've said as I've written a lot. Hope that helps.
