IGCSE Chemistry Paper-1: Specimen Questions with Answers 15 - 17 of 99

Question 15

Question

MCQ▾

What is the relative molecular mass, Mr, of HNO3?

Choices

Choice (4)

a.

63

b.

31

c.

5

d.

32

Answer

a.

Explanation

Relative molecular mass is the sum of all the relative atomic masses of the atoms in a molecule.

H= 1, N= 14, O= 16

Therefore

Question 16

Describe in Detail

Essay▾

The diagram shows how to obtain pure water from seawater. Where do water molecules lose energy?

Process of Getting Pure Water

Explanation

Here, Sea water contains .

  • So, to obtain pure water () , there is a process called desalination is used to convert salt water into pure water.

Desalination Process:

  • In this process, sea water is heated by any Bunsen flame as shown in upper figure to convert sea water into gas state.
  • Then this gas is condensed to make it liquid which is called distillation process which gives pure water.

Chemical Formula:

Question 17

Question

MCQ▾

Element X forms an acidic, covalent oxide.

Which row shows how many electrons there could be in the outer shell of an atom of X?

Choices

Choice (4)

a.

1 = N 2 = Y 6 = N 7 = Y

b.

1 = N 2 = N 6 = Y 7 = Y

c.

1 = Y 2 = Y 3 = N 6 = N 7 = N

d.

1 = Y 2 = N 6 = Y 7 = N

Answer

b.

Explanation

They must be 4,5,6 or 7. For example element having 7 electrons on its outer shell such as Cl forms acidic oxide Cl207. Again element with 4 electrons on is outer shell like nitrogen forms NO2 an acidic oxide. Therefore it can have 6 or 7 electrons.

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