Atoms and Molecules Class 9

The law of conservation of mass states that

• Matter is created in a chemical reaction

• Matter is destroyed in a chemical reaction .

• Matter is either created or destroyed in a chemical reaction .

• Matter is neither created nor destroyed in a chemical reaction .

The Ratio by mass of elements Hydrogen and oxygen in water is

• 1:2

• 1:8

• 2:1

• 8:1

How many atoms ae there in a molecule of water ?

• 1

• 2

• 3

• 4

The cation present in aluminium hydroxide is that of

• Aluminium

• Oxide

• Hydrogen

• Hydroxide

The number of ions in a molecule of aluminium oxide is

• 2

• 3

• 4

• 5

The correct formula of sodium chloride

• nacl

• NACL

• NaCl

• NacL

ASSERTION-The sum of the masses of the reactants is equal to the sum of the masses of the products .

Reason-Matter is creatsed during a chemical reaction

• Both Assertion and reason are correct and reason is the correct explanation of assertion .

• Both Assertion and reason are correct but reason is notthe correct explanation of assertion .

• Assertion is true but reason is false .

• Assertion is false but reason is true .

The number of cations in a molecule of sodium sulphate is /are

• 1

• 2

• 3

• 4

When aqueous solutions of barium chloride and sodium sulphate react , the precipitate formed is

• Curdy white

• Reddish brown

• Yellow

• Green

The atomic mass of carbon is

• 6 u

• 8 u

• 12 u

• 16 u