Conservation of Mass

Q.

Who proposed the law of conservation of mass?

1. Maharshi Kannad

2. Democritus

3. Dalton

4. Lavoisier

Q.

Mass of reactants is equal to the mass of products. A reaction has the same number of atoms of different elements on either side of a chemical equation.

1. True

2. False

Q.

In a chemical reaction, the mass of the reactants is equal to the mass of the products if the reaction has the same number of atoms of different elements on either side of the chemical equation respectively.

1. True

2. False

Q.

What is the mass percentage of hydrogen in the H₂O molecule?

1. 33.33%

2. 22.22%

3. 11.11%

4. 5.55%

Q.

The law of conservation of mass was proposed by ________ in _____.

Q.

Write true or false. Correct the false statement.

The law of conservation of mass states that mass is created during a chemical reaction.

1. True
2. False

Q.

Why is it necessary to balance the number of atoms on the two sides of a skeletal chemical equation?

1. Law of conservation of mass

2. The number of atoms are representative of the mass of each element on each side of a chemical reaction

3. The skeletal equation does not show all the elements

4. There has to be a difference between skeletal and balanced equation

Q.

Law of conservation of mass states that during a chemical reaction,

1. mass remains unchanged

2. volume remains unchanged

3. temperature remains unchanged

4. none of these

Q.

The Law of conservation of mass is always violated in a chemical reaction in which gas is evolved

1. True
2. False

Q.

Why potassium nitrate is not used for laboratory preparation of oxygen?

Q. Lead nitrate on thermal decomposition produces

1. Carbon dioxide
2. Sulphur dioxide
3. carbon monoxide
4. Lead oxide

Q.

During a chemical change, mass is conserved.

1. True
2. False

Q.

Consider the following reaction.

$Cu\left(N{O}_3{)}_2\right(s)\to CuO(s)+N{O}_2(g)+O_2(g)$ Which of the following is/are correct?

1. Mass of products = mass of reactants

2. Number of atoms on either side of the reaction are equal

3. Mass of reactants is not equal to mass of products

4. Number of atoms on product side is more than the reactant side.

Q. ${\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)+\mathrm{NaOH}\left(\mathrm{aq}\right)\to \mathrm{NaCl}\left(\mathrm{aq}\right)+{\mathrm{NH}}_3\left(g\right)+H_{2}O\left(\mathrm{aq}\right)$

For the given reaction, let's assume the total mass of $N{H}_{4}ClandNaOH$ taken was 50g. After complete reaction took place, the mass of $NaCland{H}_{2}O$ obtained was 40g.Then what is the mass of ${\mathrm{NH}}_3$ gas released?

1. 20g
2. 10g
3. 50g
4. 45g

Q.

Law of conservation holds true and can be verified in a school laboratory.

1. only for precipitation reaction carried in open system

2. only for precipitation reaction carried in close system

3. for all types of chemical reactions carried in the open system

4. for all types of chemical reaction carried in close system

Q.

The Law of Conservation of mass implies that the density of reactants and products must be the same.

1. True
2. False

Q. What happens when carbon burns in air? Write the balanced chemical equation and state the nature
of the product formed.

Q.

What is the law of conservation of mass?

Q.

The gram molar weight of $N{H}_3$ is:

1. 16

2. 17

3. 18

4. 9

Q.

Consider the following reaction.

$Cu(N{O}_3{)}_2\to CuO+N{O}_2+O_2$

Which of the following are correct?

1. Mass of products = mass of reactants

2. Number of atoms on either side of the reaction are equal

3. Mass of reactants is not equal to mass of products

4. Number of atoms on product side is more than the reactant side

Q. What indicates that a chemical reaction has occurred? [3 Mark]

Q.

In an experiment, 15 gm of a compound X is heated in a closed glass container to give compounds Y and Z. The total mass of the compounds Y and Z is ______.

1. 30

2. 20

3. 15

4. 10

Q.

why is it necessary to balance an equation??

Q. Zinc sulphate contains 22.65% Zn and 43.9% H2O.If the law of constant proportions is true the mass of Zn required to give 40g of crystal is

Q.

Which law of chemical combination is referred to as the “the law of indestructibility of matter”?