Answer:
FALSE!!
Explanation:
Physical changes occur when objects or substances undergo a change that does NOT change their chemical composition. This contrasts with the concept of chemical change in which the composition of a substance changes or one or more substances combines or break up to form new substances.
7th grade science pls help
Answer: The last answer.
Explanation:
Hanif thought that more heat energy has been given out in his reaction and noor thought that both reactions gave out same amount of heat. Whose idea is correct and why?
Answer:
This question is incomplete but the missing part is in the document attached
Noor's idea is correct
Explanation:
Noor's idea is correct. This is because the temperature rise in the two experiments are the same and can be calculated as follow
Hanif's experiment: 45 - 21 = 24 °C
Noor's experiment: 42 - 18 = 24 °C
Thus, the correct idea is both reactions gave out same amount of heat
does anyone know this?
Answer:
1.24 moles
Explanation:
first find the molar mass of AgNO3, which I got 169.877
then, divide the number of moles used by the Molar mas
210/169.877 = 1.2361 = 1.24
Since, the molar ratios of AgNO3 and Ag are the same (2:2), the answer will be 1.24
How many molecules of ammonia will be produced?
4
2
8
6
Answer:
4
Explanation
i just know the answer
Which one will diffuse faster Ammonia or carbon dioxide Why?
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Ultrasound and Magnetic Resonance Imaging (MRI), are technologies used to create images of a patient's internal features. In many instances, either technology can be used when diagnosing patients. However, ultrasound is often preferred for diagnosing moving features, while MRI is often preferred for diagnosing features surrounded by air or dense bone. Based on these differences, which of the following best describes the waves used by these technologies?
A.
Ultrasound uses sonar technology with sound waves, while MRI uses electromagnetic waves.
B.
Ultrasound and MRI both use electromagnetic waves because electromagnetic waves require a medium through which to travel.
C.
Ultrasound and MRI both use sonar technology with sound waves because sound waves are not affected by a change in medium.
D.
Ultrasound uses electromagnetic waves, while MRI uses sonar technology with sound waves.
Ultrasound uses sonar technology with sound waves while MRI uses electromagnetic waves.
What are electromagnetic waves?
The electromagnetic radiation consists of electromagnetic waves made up of electromagnetic field which are capable of propogating through space and carry the radiant electromagnetic energy.
The radiation are composed of electromagnetic waves which are synchronized oscillations of electric and magnetic fields . They are created due to change which is periodic in electric as well as magnetic fields.
In vacuum ,all the electromagnetic waves travel at the same speed that is with the speed of air.Ultrasound uses sonar technology with sound waves while MRI uses electromagnetic waves.There are seven type of electromagnetic waves depending on the energy and frequency of the waves. These waves are a solution of Maxwell's equation.
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Which element will never react, neon (Ne) or hydrogen (H)?
Answer:
Neon(Ne)
Explanation:
Neon will not react because it is a noble gas and had 8 electrons.
Answer:
Neon
Explanation:
Neon has a full octet and is a noble gas, hydrogen can still react because it can share or give its electron to another element
Help you’ll get 12 points
Answer:
a
a
b
a
b
Explanation:
hope this is right! hope it helps :)
What is an ore? An object that has been recycled, an article of clothing that’s made from natural fiber, a rock that contains enough of a metal to be worthwhile to extract, and a fossil fuel that can be burned to generate electricity.
Answer:
cccccccc
Explanation:
got it right
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Write chemical equations for the following single-replacement reactions that might occur in water. If no reaction occurs, write NR in place of the products.
a.) nickel + magnesium chloride
b.) calcium + copper (II) bromide
c.) potassium + aluminum nitrate
d.) magnesium + silver nitrate
Answer:
Explanation:
A) No reaction occurs. It is really hard to replace Mg once a reaction has taken place. (NR)
B) Ca + Cu(ii)Br2 ==> Cu + CaBr2. Calcium only ionizes to Ca2+
C) 3K + Al(NO3)3 ===> Al + 3KNO3 Potassium is very reactive.
D) Mg + AgNO3 ====> Mg(N03)2 + Ag
9. A graduated cylinder is filled with water to a level of 40.0 mL. When a piece of copper is lowered into the cylinder, the water level rises to 63.4 mL. Find the volume of the copper sample. If the density of the copper is 8.9 g/cm3, what is its mass?
Answer:
Mass = 208.26 g
Explanation:
Given data:
Volume of water = 40.0 mL
Volume of water + copper = 63.4 mL
Volume of copper = ?
Density of copper = 8.9 g/cm³
Mass of copper = ?
Solution:
Volume of copper:
Volume of copper = (Volume of water + copper ) - Volume of water
Volume of copper = 63.4 mL - 40.0 mL
Volume of copper = 23.4 mL
Mass of copper:
density = mass/volume
8.9 g/cm³ = mass/23.4 mL
cm³ = mL
Mass = 8.9 g/mL × 23.4 mL
Mass = 208.26 g
help please this is due soon!!
Answer:
33
Explanation:
Elements that can be very dangerous but form useful materials when combined with other elements
Answer Choices:
Atomic Mass
Atomic Number
Halogens
Metals
Noble Gases
Non - Metals
Answer: Halogens
Explanation:
Halogens include elements like Fluorine, Chlorine, Iodine and Bromine. These elements can be dangerous to humans especially when used in large quantities.
When combined with other elements however, they can form very useful materials. Chlorine for instance forms salt when combined with sodium. Fluorine becomes very useful in toothpaste to protect teeth and bromine can be used in pesticides.
What are the different chemical properties of the element Cobalt?
Answer:
It is a hard ferromagnetic, silver-white, lustrous, brittle element.
It is stable in air and does not react with water.
Like other metals, it can also be magnetized.
With dilute acids, it reacts slowly.
The metal melts at 1495 °C and boils at 2927 °C
Explanation:
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Cells are differentiated when
A they divide
B they grow in size
C genes are turned on or off
D they all perform the same function
Answer:
D I think.............
What is the element Ar classified as in the periodic table?
A- a noble gas
B- a halogen
C- a metalloid
D- a metal
The elements are the basic units that are indivisible and are defined by protons. The element Ar is classified as a noble gas in the periodic table. Thus, option A is correct.
What is a noble gas?Noble gas occupies the zero group in the periodic table and is unreactive and monoatomic gas that shares similar properties of being colorless, and odorless.
The gases helium, argon, neon, xenon, and krypton are noble gases that are inert, stable, and have low reaction rates that make them used in standard conditions.
The seven noble gases are unable to bond with the atoms of the other elements which makes them less reactive. Because of their less reactive nature, they are also called inert gases.
Therefore, argon (Ar) is a noble gas.
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How can the shape of a molecule determine its polarity.
Answer:
The shape of the molecule will determine the direction of each of the individual bond dipoles, and thus, will always play a role in determining the polarity of the molecule as a whole.
Try to see if your answer is correct from that :)
Explanation:
When one side of a molecule (or polyatomic ion) is more positive (or negative) than the other, the molecule is said to be polar. The correct option is C.
Thus, When the bonds' polarities do not balance out, this happens.
As opposed to CO2, which is a nonpolar molecule, each carbon-oxygen link in CO2 is polar.
Due to the linear nature of the molecule, the two bonds point in different directions.
Their opposite polarities cause their effects to cancel. The molecule's two sides are equal; neither is more adverse than the other.
Thus, When one side of a molecule (or polyatomic ion) is more positive (or negative) than the other, the molecule is said to be polar. The correct option is C.
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You have a radioactive isotope with a mass of 400 grams. The sample has a half life of 5 days. How much is left after 25 days have passed?
Answer:
Amount left after 25 days = 12.5 g
Explanation:
Given data:
Mass of sample = 400 g
Half life of sample = 5 days
Mass left after 25 days = ?
Solution:
First of all we will calculate the number of half lives passes in given time period.
Number of half lives = Time elapsed / Half life
Number of half lives = 25 days/ 5 days
Number of half lives = 5
At time zero = 400 g
At 1st half life = 400 g/2 = 200 g
At 2nd half life = 200 g/2 = 100 g
At 3rd half life = 100 g/2 = 50 g
At 4th half life = 50 g/2 = 25 g
At 5th half life = 25 g/2 = 12.5 g
Hydrogen atoms do not repel each other within a star
When salt is added to water, the entropy, S,
of the system can be described by an
inequality.
Ssolution > Swaler + Ssalt
According to the inequality, what increases
when salt is added to the water?
A. Internal energy
B. state of disorder
C. number of particles
D. strength of attraction between particles
Answer:
C. number of particles
Explanation:
Entropy is the measure of disorderliness of a system. Remember that when you dissolve salt in water, you increase the number of particles in the solution. The greater the number of particles in solution, the greater the entropy of the solution system.
Hence dissolution of a salt in water increases the entropy by increasing the number of particles in solution leading to the inequality; Ssolution > Swater + Ssalt.
Which of these elements is the most reactive
Answer:
What elements?
Explanation:
The alkali metals are softer than most other metals. Cesium and francium are the most reactive elements in this group. Alkali metals can explode if they are exposed to water.
Not sure if this what you were talking about but here
This from google btw not gonna lie
Which is not a direct classification of matter?
a. Element
b. Homogenious Mixture
c. Mixture
d. Pure Substance
Answer:
d
Explanation:
Triangle ABC has been dilated about point A by a scale factor of One-third. Triangle A B C. Side A C has a length of 39, side A B is 30, side C B is 48. Triangle A prime B prime C prime. What are the lengths, in units, of the three sides of Triangle A prime B prime C prime? 10, 12, 13 10, 16, 13 90, 124, 97 90, 144, 117
Answer:
10, 16, 13
Explanation: I just took the test and it was correct :)
which metal is liquid and has silvery-white color.
Answer:
Mercury
Explanation:
It is also highly toxic
it's the third pic
How many days does it take for 16 g of palladium-103 to decay to 1.0 g? The half-life of palladium-103 is 17 days.
Answer: It will take 68 days for the palladium to decay.
Explanation: ima smart dude
A sample of a fluid has a mass of 10g and volume of 2 ml. What is the density of this fluid?
A. 10 g/ml
B. 20 g/ml
C. 5 g/ml
D. 2 g/ml
Answer:
Is the letter C
Explanation:
You have to divide the mass with the volume
Whats the most common chemical element in the earths crust?
Answer:
Oxygen
Explanation:
it is 47% of the earth's crust.the 2nd would be silicon if you wanted to know.
have a good day maam!
What is the molecular formula of gypsum salt ?
Gypsum is composed of calcium sulphate (CaSO4) and water (H2O). Its chemical name is calcium sulphate dihydrate (CaSO4. 2H2O).
Magnetism is an example of a property of what?
A) behavior
B)chemistry
C)flammability
D) mass
Answer:
A) behavior
Explanation:
