CIE Chemistry Paper-1: Specimen Questions 48 - 50 of 99

Question number: 48

MCQ▾

Question

Which of the following statements are incorrect in regard to alkanes?

  1. Alkanes are saturated hydrocarbons.
  2. All the carbon atoms present are bound to each other carbon atoms by double bond
  3. All the carbon atoms present are bound to each other carbon atoms by double bond

Choices

Choice (4) Response
a.

2) and 3)

b.

Only 2)

c.

Only 3)

d.

1) and 3)

Answer

a.

Explanation

Alkanes are the simplest organic molecules, consisting of only carbon and hydrogen and with only single bonds between carbon atoms. Alkanes are used as the basis for naming the majority of organic compounds (their nomenclature). Alkanes have the general formula CnH2n + 2.

Question number: 49

MCQ▾

Question

Which two gases are formed when electrolysis of water is carried out?

Electrolysis of water

Electrolysis of water

Two gases are formed when electrolysis of water takes place

Choices

Choice (4) Response
a.

Hydrogen and Oxygen

b.

Hydrogen and Carbon di oxide

c.

Hydrogen and Nitrogen

d.

Oxygen and nitrogen

Answer

a.

Explanation

Water ionises to produce hydrogen (H+) ions and hydroxide (OH¯) ions. These are often displaced from solution to give hydrogen gas and oxygen gas. The substance formed at the cathode is usually hydrogen, unless the solution contains copper or silver ions, in which case, copper or silver will form at the cathode.

Question number: 50

MCQ▾

Question

Which among the below is example of double covalent molecular structure?

Choices

Choice (4) Response
a.
Structure of Oxygen Bonding

Structure of Oxygen Bonding

Finding the Oxygen bonding

b.
Structure of Chlorine Bonding

Structure of Chlorine Bonding

Finding the chlorine bonding

c.
Structure of Nitrogen Bonding

Structure of Nitrogen Bonding

Finding the Nitrogen bonding

d. None of the above

Answer

a.

Explanation

Double bond is formed by the sharing of two pairs of electrons of the valence shell.

Example: Oxygen molecule (O = O)

The atomic number of oxygen is 8. It requires two electrons to achieve the nearest stable inert gas configuration, which is neon. To achieve this, two oxygen atoms contribute two unpaired electrons to produce two bond pairs. Thus, they share these two electron pairs to form a double bond.

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