CIE Chemistry (US-0439): Specimen Questions with Answers 166 - 167 of 240

Question number: 166

MCQ▾

Question

The number of oxygen molecules present in of oxygen gas is ________.

(Given that the Relative Atomic Mass of oxygen is

Choices

Choice (4) Response

a.

130

b.

110

c.

140

d.

120

Answer

d.

Explanation

Relative

Number of molecules in

atoms of oxygen combine to form a stable oxygen molecule.

Relative

Gram Molecular Mass of a substance is its Relative Molecular Mass expressed in grams.

Thus

Now .

So

So .

Therefore 640 g of oxygen has molecules

Question number: 167

Short Answer Question▾

Write in Short

All metal nitrates decompose when heated. A few form a nitrite and oxygen. Most form the metal oxide, oxygen and a brown gas called nitrogen dioxide.

Complete the equation for the action of heat on lead (II) nitrate.

Explanation