Quiz on the Law of Conservation of Mass

The amount of matter in an object is its ____________.

Answer explanation

The amount of matter in an object is referred to as its mass. Mass is a fundamental property that quantifies the amount of material present, distinguishing it from weight, which is the force exerted by gravity on that mass.

• 2W
• F
• H
• 2P

Tags

NGSS.MS-ETS1-1

NGSS.MS-ETS1-2

Please state the Law of Conservation of Mass in your own words.

Answer explanation

The Law of Conservation of Mass states that matter cannot be created or destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Mass is conserved in physical but not chemical changes in matter.

• True

• False

Answer explanation

Mass is conserved in both physical and chemical changes. Therefore, the statement is false, as it incorrectly claims that mass is conserved only in physical changes.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

New substances are formed when the ​ (a)   of substances are rearranged during a​ (b)   reaction. The law of ​ (c)   of mass states that the total number of atoms of each ​ (d)   is not created or ​destroyed during a chemical reaction. Instead, the atoms are ​ (e)   to form new substances.

• atoms
• chemical
• conservation
• element
• rearranged
• compound
• physical

Tags

NGSS.MS-PS1-5

When a candle burns, all that remains is a small puddle of wax. The puddle of wax has less mass than the original candle. The rest of the candle’s mass was

• destroyed

• changed to gasses

• measured incorrectly

• none of above

Answer explanation

When a candle burns, the wax melts and some of it is converted into gases (like carbon dioxide and water vapor) through combustion. This explains why the remaining puddle of wax has less mass; it was changed to gases.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A puddle of water slowly shrinks in the sun. After a few hours, the puddle has dried up completely. Is this an exception to the Law of Conservation of Mass? Please explain.

Answer explanation

No, this is not an exception to the Law of Conservation of Mass. The water evaporates into the air, maintaining the total mass. The mass is conserved, just transformed from liquid to vapor.

Tags

NGSS.MS-ESS2-4

NGSS.MS-PS1-4

Fire destroys the mass of the fuel that it burns.

• True

• False

Answer explanation

The statement is false because fire does not destroy the mass of the fuel; it converts it into energy and other byproducts. The total mass is conserved according to the law of conservation of mass.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Assume that 3 grams of compound A reacts with 6 grams of compound B.

A solid white precipitate is produced during this reaction, and some gas is also released. The precipitate has a mass of 2 g. What is the mass of the gas that was produced? Please show all your work.

Answer explanation

Total mass before reaction = 3g (A) + 6g (B) = 9g. After reaction, mass = mass of precipitate + mass of gas. 9g = 2g (precipitate) + mass of gas. Therefore, mass of gas = 9g - 2g = 7g.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

The products of a chemical reaction can never have greater mass than the reactants.

• True

• False

Answer explanation

According to the law of conservation of mass, the total mass of reactants in a chemical reaction equals the total mass of the products. Therefore, the products can never have greater mass than the reactants, making the statement true.

Tags

NGSS.MS-PS1-5