Answer:
a. H + d. Na
Explanation:
This is Mixture of H and Na. Because of H and in the emission and Absorption spectrum of H Total 5 lines [Red, Green, Blue and Purple (2)) are present and in the spectrum of Na Two yellow lines are present. In the mixture all this lines are are also 5 + Present. Total lines are 5+2= 7 (H+ Na)
Therefore, the answer is a. H + d. Na
1) The percentage of oxygen in dry air is _______
A. 0.1
B. 1.0
C. 21
D. 79
2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?
A. Oxygen
B. Carbon dioxide
C. Ammonia
D. Nitrogen
Answer:
1) The percentage of oxygen in dry air is _______
C. 21
2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?
B. CARBON DIOXIDE
Hope it helps
have a nice day
Answer: The percentage of oxygen in dry air is . 21
Explanation: Ammonia gases was present in large amounts in the easth7s earliest atmosphere
Hope it will help you
A solar energy company learns of several recent cyber-attacks targeting other companies in their industry and realizes they could be next. The company initiates an analysis to weigh the measures needed to counter the potential threat and minimizing the impact to their business in case those are exploited. Which security principle is illustrated in this example?
A 4.369 g sample of metal is placed in a flask. Water is added to the flask and the total volume in the flask is read to be 126.4 ml. The mass of the water, flask, and metal is 268.5 g. If the mass of the flask is 139.3 g and the density of water is 1.000 g/mL, the density of the solid is ________ g/cm3.
Answer:
Density of the solid=[tex]2.78 g/cm^3[/tex]
Explanation:
We are given that
Mass of sample of metal=4.369 g
Volume in the flask, V=126.4 ml
Mass of water, flask, and metal=268.5 g
Mass of flask=139.3 g
Density of water=1.000 g/mL
We have to find the density of the solid.
Mass of water=268.5-4.369-139.3=124.831 g
Volume of water=[tex]\frac{Mass\;of\;water}{density\;of\;water}[/tex]
Volume of water=[tex]\frac{124.831}{1}=124.831 mL[/tex]
Volume of solid=126.4 ml-124.831 mL
=1.569mL
Now,
Density of the solid=[tex]\frac{mass\;of\;solid}{volume\;of\;solid}[/tex]
=[tex]\frac{4.369}{1.569}[/tex]
[tex]=2.78g/mL[/tex]
1mL=1 cubic cm
Therefore,
Density of the solid=[tex]2.78 g/cm^3[/tex]
A sample of substance "B" has a mass of 37.6g contained in a volume of
9.65mL. What is the density of substance "B"? (Report your answer with 3
s.f. E.G.: 6.00g/mL)
Answer:
3.90g/mL
Explanation:
To find the density of a substance, divide the mass by the volume.
So, 37.6 / 9.65 = 3.89637
then round to 3 significant figures
Good luck!
The reversible reaction, 4HCl(g) + Si (s) ⇌ SiCl4 (l) + 2H2 (g) , would be classified as a ______________ reaction.
exothermic
endothermic
homogeneous
heterogeneous
Answer:
endothermic
Explanation:
endothermic reactions absorb heat from their surroundings, in this reaction the reactants are gas and solid and the products are liquid and gas, implying heat was absorbed to turn a solid to a liquid.
Heat is most closely related to which kind of energy?
O nuclear
electrical
thermal
chemical
Answer:
C thermal
Explanation:
Which statement correctly describes a product of a reaction within
photosynthesis?
O A. ATP is produced during the light reactions.
O B. Carbon dioxide is produced during the light reactions.
O C. Oxygen is produced during the Calvin cycle.
OD. NADPH is produced during the Calvin cycle.
Answer:
B
pls correct me if im wrong
every action produces an equal and opposite -- ---------- when one object exterts a force on another object,the second object pushes back with the same amount of---------
someone knows the answer
Cuál o cuáles de las siguientes características son correctas para la mayoría de los compuestos del carbono?
I) Los compuestos del carbono son solubles en disolventes no polares como el hexano, benceno, éter, etc.
II) Los compuestos del carbono generalmente presentan puntos de fusión y de ebullición bajos
III) La gran mayoría de los compuestos del carbono son combustibles, sean estos, gaseosos, líquidos o sólidos
IV) El enlace covalente es característico de los compuestos del carbono
Todas son correctas
II
I y IV
I, III y IV
Answer:
Todas son correctas
Explanation:
I) Los compuestos del carbono son solubles en disolventes no polares como el hexano, benceno, éter, etc. VERDADERO. La mayoría de los compuestos de carbono son apolares, y basados en la regla: Similar disuelve similar, podemos presumir que la mayoría de compuestos de carbono se disuelven en solventes no polares.
II) Los compuestos del carbono generalmente presentan puntos de fusión y de ebullición bajos. VERDADERO. Al ser sustancias apolares, sus fuerzas electrostáticas son bajas. De la misma manera, como su masa atómica es pequeña, las fuerzas de Van der Waals son despreciables haciendo que sus puntos de fusión y ebullición sean bajos respecto a sustancias de estrucutra similar.
III) La gran mayoría de los compuestos del carbono son combustibles, sean estos, gaseosos, líquidos o sólidos. VERDADERO. Los gases (Como el gas natural) son combustibles usados para cocina. Los líquidos (Como la gasolina) son combustibles y bastante inflamables. Los sólidos (Como la madera) se usan como combustibles para hacer asados o son el combustible en incendios forestales.
IV) El enlace covalente es característico de los compuestos del carbono. VERDADERO. La polaridad del carbono es neutral haciendo que la mayoría de los enlaces que forma sean covalentes.
Todas son correctas
.
Unlike a theory, a scientific law describes an observed pattern without attempting to _____ it.
explain
prove
test
verify
hey armies.. how are you doing
Answer:
Nice and you
Explanation:
Please Mark me brainliest
What is a substance that decreases the rate of a chemical reaction called? (5 points)
What is a substance that decreases the rate of a chemical reaction called? (5 points)
Catalyst
Inhibitor
Product
Reactant
Answer:
inhibitor :)
Explanation:
Catalysts speed the reaction up, and the other 2 are essential for the reaction to work, so an inhibitor :)
Answer:
Inhibitor
Explanation:
What is the molarity of the solution formed by dissolving 80. G of NAOH(s) into water to give a total volume of 4.00 l
Answer:
0.5 M
Explanation:
From the question given above, the following data were obtained:
Mass of NaOH = 80 g
Volume of solution = 4 L
Molarity =?
Next, we shall determine the number of mole in 80 g of NaOH. This can be obtained as follow:
Mass of NaOH = 80 g
Molar mass of NaOH = 23 + 16 + 1
= 40 g/mol
Mole of NaOH =?
Mole = mass / molar mass
Mole of NaOH = 80 / 40
Mole of NaOH = 2 moles
Finally, we shall determine the molarity of the solution. This can be obtained as follow:
Mole of NaOH = 2 moles
Volume of solution = 4 L
Molarity =?
Molarity = mole / Volume
Molarity = 2/4
Molarity = 0.5 M
Therefore, the molarity of the solution is 0.5 M.
Suppose that you chose sodium carbonate to precipitate the chromium ions from a solution of chromium (III) chloride. Write and balance the equation of this double-displacement reaction.
If the solution has a volume of 520 mL and the concentration of chromium (III) chloride is 0.224 M, how many grams of sodium carbonate should you add to the solution to precipitate out all the chromium ions?
Answer:
18.5g Na2CO3
Explanation:
Chromium (III) chloride, CrCl3, reacts with Na2CO3 as follows:
2CrCl3 + 3Na2CO3 → Cr2(CO3)3(s) + 6NaCl
Where 2 moles of CrCl3 react with 3 moles of Na2CO3 to produce 1 mole of Cr2(CO3)3 -The precipitate-
To solve this question we need to find the moles of CrCl3 added. With the chemical equation we can find the moles of Na2CO3 and its mass as follows:
Moles CrCl3:
520mL = 0.520L * (0.224mol/L) = 0.116 moles CrCl3
Moles Na2CO3:
0.116 moles CrCl3 * (3 mol Na2CO3 / 2mol CrCl3) = 0.175 moles Na2CO3
Mass Na2CO3 -Molar mass: 105.99g/mol-
0.175 moles Na2CO3 * (105.99g/mol) = 18.5g Na2CO3
How many ATOMS of boron are present in 3.61 grams of boron trifluoride ?
Hi there!
[tex]\large\boxed{3.203 * 10^{22} atoms}[/tex]
We can use the following conversions to solve:
Total mass --> amount of mols --> amount of atoms (Avogadro's number)
Begin by calculating the amount of boron trifluoride in 3.61 grams:
3.61 g * (1 mol BF₃ / 67.8 g) ≈ 0.0532 mol BF₃
Use avogadro's number to convert:
0.0532 mol * 6.02× 10²³atoms / 1 mol = 3.203 × 10²² atoms
Help me please guys
Answer:
D. 2
Explanation:
On the right side of the equation:
Al has 1, Zn has 3, NO3 has 6
But on the left side:
Al has 1, Zn has 1, NO3 has 3
1. So, if we add a coefficient of 2 to Al(NO3)3, then NO3 now has 6-which is what it needs.
2. But now the Al on the right side of the equation is not balanced, so give it a coefficient of 2.
3. To make the Zn balance, just add a coefficient of 3 on the left side of the equation.
Which leaves us with:
2Al + 3Zn(NO3)2 --> 2Al(NO3)3 + 3Zn
And now there are the same number of each compound on both sides of the equation.
Good luck! If you have any questions on this answer leave a comment :)
which among the following pairs are not isotopes?
Lead is a toxic metal that affects the central nervous system. A Pb-contaminated water sample contains 0.0012 % Pb by mass. What volume of the water in milliliters contains 100 mg of Pb
Answer:
8.3 × 10³ mL
Explanation:
Step 1: Calculate the mass of water that contains 100 mg of Pb
The concentration of Pb in the sample is 0.0012% by mass, that is, there are 0.0012 g of Pb every 100 g of water. The mass of water that contains 100 mg (0.100 g) of Pb is:
0.100 g Pb × 100 g Water/0.0012 g Pb = 8.3 × 10³ g Water
Step 2: Calculate the volume corresponding to 8.3 × 10³ g of water
Since the solution is diluted, we will assume the density of the sample is equal than the density of water (1 g/mL).
8.3 × 10³ g × 1 mL/1 g = 8.3 × 10³ mL
The volume of the water in milliliters contains 100 mg of Pb is;
V = 8.3 × 10³ mL
Volume of SolutionWe are given the concentration of Pb in the sample as 0.0012% by mass.
That means that there are 0.0012 g of Pb in every 100 g of water.
Thus, the mass of water that contains 100 mg (0.100 g) of Pb is calculated as;
(0.100 g Pb × 100 g of Water)/0.0012 g of Pb = 8.3 × 10³ g of Water
Now, we know that the density of water (1 g/mL) but we are not given the density of the sample.
Thus, since the solution is diluted we can equally say that;
Density of sample = 1 g/mL
Formula for Volume is;
V = mass/density
Thus;
V = 8.3 × 10³ g/1 g/mL
V = 8.3 × 10³ mL
Read more about Volume of solution at; https://brainly.com/question/17055828
calculate the mass of solute in 500cm³ of 1.5mol/dm³ sodium hydroxide solution
Answer: The general formulae for moles is n=m/mr so now we have being given to find the mass so all we have to do is to change subject
Explanation: so we have to change subject in this question to m= n× mr . so in the question below we have being given the mole as 1.5mol/dm³ so all we have to do is to find the molecular relative mass(mr) .
to find the molecular relative mass of sodium hydroxide (NAOH) we add all of the atomic masses of all the atoms present so here we have sodium oxygen and hydrogen atoms present.
NA=23 O=16 H=1 so we add 23+16+1=40 so 40 is our molecular relative mass
now we fix it in our formulae which is m=n× mr
m=1.5× 40 =60 so our mass is 60grams or 60g
HOPE THIS HELPS!!!! if i made a mistake our MAY answer may be wrong feel free to comment
PLS HELP!!
Compare and contrast an electrolytic cell with a voltaic cell. Provide one example where both are present in daily life.
Answer:
See explanation
Explanation:
An electrolytic cell functions by a non spontaneous chemical process. Energy is supplied in the form of electricity through a battery to drive the electrochemical process.
A voltaic cell functions by a spontaneous chemical process. Energy or work can be derived from a voltaic cell.
When iron is rusting, a natural voltaic cell is set and the iron is converted to hydrated iron III hydroxide. The set up used for the extraction of sodium metal from brine functions on the basis of electrolysis.
Blood tests can be used to check a person's blood glucose and hormone levels. The tabular column given below shows the result of two blood tests carried out on three people to check their blood glucose levels. Person 1 is healthy
Answer:
In after fasting test, Person 2 has slightly higher blood glucose level than person 1.
In after drinking glucose test, Person 3 has much high glucose level than person 1.
Explanation:
Blood sugar test determines the level of glucose present in body. The test can be taken after intake of food / glucose or after fasting for 12 hours. Results of both tests are compared to identify level of glucose present in human body. In after fasting test person has higher glucose and in another test person 3 has higher glucose level.
Diego is trying to lift a piano to the second floor of his house. Diego uses a pulley system and gives a big lift to the piano.The piano moves upward, then stops, and then it starts to fall to the ground. (The direction of the force of gravity is negative.) Which list best describes the forces on the piano in the proper order
Answer:
positive force → balanced force → negative force
Explanation:
np
Answer:
positive force → balanced force → negative force
Explanation:
:)))
What kind of reactions are redox reactions
A reaction in which reduction and oxidation take place simultaneously known as a redox reaction.
Nitrogen dioxide gas is dark brown in color and remains in equilibrium with dinitrogen tetroxide gas, which is colorless.
2NO2(g) ⇌ N2O4(g)
When a light brown colored mixture of the two gases at equilibrium was moved from room temperature to a higher temperature, the mixture turned dark brown in color.
Which of the following conclusions about this equilibrium mixture is true?
This reaction is exothermic because the system shifted to the left on heating.
This reaction is exothermic because the system shifted to the right on heating.
This reaction is endothermic because the system shifted to the left on heating.
This reaction is endothermic because the system shifted to the right on heating.
Answer:
This reaction is exothermic because the system shifted to the left on heating.
Explanation:
2NO₂ (g) ⇌ N₂O₄(g)
Reactant => NO₂ (dark brown in color)
Product => N₂O₄ (colorless)
From the question given above, we were told that when the reaction at equilibrium was moved from room temperature to a higher temperature, the mixture turned dark brown in color.
This simply means that the reaction does not like heat. Hence the reaction is exothermic reaction.
Also, we can see that when the temperature was increased, the reaction turned dark brown in color indicating that the increase in the temperature favors the backward reaction (i.e the equilibrium shift to the left) as NO₂ which is the reactant is dark brown in color. This again indicates that the reaction is exothermic because an increase in the temperature of an exothermic reaction will shift the equilibrium position to the left.
Therefore, we can conclude that:
The reaction is exothermic because the system shifted to the left on heating.
The reaction is exothermic and the equilibrium position shifted to the left hand side.
An exothermic reaction is one in which heat is given out. Hence, the equilibrium position moves towards the left when the temperature is increased in an exothermic reaction.
Given the reaction, 2NO2(g) ⇌ N2O4(g) the appearance of a dark brown gas at high temperature implies that the reaction is exothermic and the equilibrium position shifted to the left hand side.
Learn more about exothermic reaction: https://brainly.com/question/15308590
how to make a sponge
Answer:
Synthetic sponges are made of three basic ingredients: cellulose derived from wood pulp, sodium sulphate, and hemp fiber. Other materials needed are chemical softeners, which break the cellulose down into the proper consistency, bleach, and dye.
Explanation:
IDK, BUT HOPE IT HELPS?
What dose science do
Explanation:
Science, any system of knowledge that is concerned with the physical world and its phenomena and that entails unbiased observations and systematic experimentation. In general, a science involves a pursuit of knowledge covering general truths or the operations of fundamental laws.
A student makes several observations about a piece of iron. Which observation describes a chemical property of the iron?
Answer:
An example of a chemical property of iron would be that it is capable of combining with oxygen to form iron oxide, or rust.
Explanation:
You have no choice listed, so I provided an example.
define hydroscopy in chemistry
Answer: A hygroscopic substance is one that readily attracts water from its surroundings, through either absorption or adsorption
Explanation:
Hello, if any of y'all don't mind, can one of you answer these 5 questions.
Answer:
4.. increases
5..lowers
6.. increases
7.. increases
8.. speed
Answer:
When a substance is heated, its temperature rises because its molecules move faster and gain thermal energy. Temperature measures the "hotness" or "coldness" of an object. The term heat refers to thermal energy being transferred from a hotter system to a cooler one.
a) the use of heat energy to react carbon dioxide with water to produce oxygen. b) a chemical reaction between carbohydrates and oxygen to produce carbon dioxide, water, and heat energy. c) a photochemical reaction involving carbon dioxide and water to produce carbohydrates and oxygen. d) a photochemical reaction involving carbon dioxide and oxygen to produce water and oxygen.
Answer: b) a chemical reaction between carbohydrates and oxygen to produce carbon dioxide, water, and heat energy
Explanation:
Based on the options, I assume that this is talking about the process of respiration. Respiration allows living things to produce energy by reacting carbohydrates with oxygen.
This results in the release of energy in the form of heat in a cell and also the formation of carbon dioxide and water. This type of respiration is known as Aerobic respiration.
