Matter and chemical formulae class 7

Identify the pair of elements.

Gold, Air, cement, iron, oxygen, water

• Air, cement

• Gold, Air

• iron, water

• iron, oxygen

Which of the following is not a compound?

Sea water, Ferrous sulphide, limestone, carbondioxide

• limestone

• Ferrous sulphide

• carbondioxide

• Sea water

Latin name and symbol of Lead is -

• Plumbum, PB

• Stannum, Sn

• Plumbum, Pb

• Ferrum, Fe

Number of atoms present in (NH4)2S is -

• 10

• 12

• 9

• 11

The atomicity of ozone is -

• 0

• 1

• 3

• 2

Valency of all noble gases are

• 0

• 1

• 2

• 3

xPb(NO3)2 = yPbO + zNO2 + O2

The value of x, y and z are -

• 4, 2, 2

• 2, 4, 2

• 2, 4, 4

• 2, 2, 4

The valeny of mercury in HgCl2 is -

• 1

• 2

• 3

• None of the above

Which one is correct?

I. Molecules do not exist freely.

II. Elements can be further divided.

III. Sodium is a monoatomic element.

IV. Atoms take part in chemical reactions.

• Only III and IV

• Only II, III and IV

• Only I and II

• All are correct

2N represents -

• One molecule of nitrogn

• Two atoms of nitrogen in chemically combined state

• Two atoms of nitrogen in chemically uncombined state

• Two molecules of nitrogn