Atoms and Molecules

"In a chemical reaction, atoms can neither be created nor destroyed." This statement is supported by:

• Law of conservation of mass

• Law of definite proportion

Atomic mass unit is equal to the:

• Mass of 1/12th of C-14 atom

• Mass of 1/12th of C-13 atom

• Mass of 1/12th of C-12 atom

"Atoms combine in fixed ratio to form compounds." This statement is supported by:

• Law of conservation of mass

• Law of definite proportion

Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of oxygen would be required to react completely with 3 g of hydrogen gas?

• 8 g

• 16 g

• 24 g

• 32 g

Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of hydrogen would be required to react completely with 56 g of oxygen gas?

• 448 g

• 8 g

• 7 g

• 1 g

How many atoms are present in phosphate ion?

• 12

• 2

• 5

• 9

Phosphate ion is a:

• Anion

• Cation

• Neutral ion

Phosphate ion has a valency of:

• 4

• 3

• 2

• 1

Which of the following is not a polyatomic ion?

• Sulphide

• Sulphite

• Sulphate

Sulphide is an ion formed from only one type of atoms. (True / False)

• True

• False

• Can be true or false