CIE Chemistry Paper-1: Specimen Questions 56 - 58 of 99

Question number: 56

MCQ▾

Question

Three elements Chlorine, Bromine and iodine have similar properties and they form a Dobereiner’s triad. If the atomic mass of chlorine is 35.5 and that of iodine is 126.9. What will be the atomic mass of Bromine (approx. value)

Choices

Choice (4) Response
a.

99.9

b.

89.9

c.

Insufficient data

d.

79.9

Answer

d.

Explanation

According to Dobereiner’s triad

Atomic mass of Bromine = Average of atomic masses of Cl and I

Now, = Average of atomic masses of Cl and I = 35.5+126.92

=162.42=81.2

Therefore 79.9 will be the atomic mass.

Question number: 57

MCQ▾

Question

Electron configuration of an element X is 1s22s22p63s23p64s23d3, which one of the following statements are true for X element.

i) Period number of X is 4 and it is transition element

ii) X is a non metal

iii) Valence electrons of X are in “s” and “d” shells.

Choices

Choice (4) Response
a.

ii) and iii)

b.

i) andii)

c.

i) and iii)

d. All of the above

Answer

c.

Explanation

X element has electron configuration;

X: 1s22s22p63s23p64s23d3

Period of the element is equal to highest energy level of electrons or principal quantum number.

Therefore, X is in period 4

The group to which it belong will be 3 + 2=5 B group. Therefore is a metal

Question number: 58

MCQ▾

Question

Which of the following is a type of decomposition reaction:

Choices

Choice (4) Response
a.

Displacement

b.

Thermal

c.

Electric

d. None of the above

Answer

b.

Explanation

The reaction in which heat energy is given to the substance and substance breaks into two or more simpler substances is called thermal decomposition reaction.

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