IGCSE Chemistry Paper-1: Specimen Questions with Answers 90 - 92 of 99

As we move from left to right , what impact does it have on the atomic size of the elements.

Answer

c.

Explanation

Atomic radius decreases from left to right within a period. This is caused by the increase in the number of protons and electrons across a period. One proton has a greater effect than one electron; thus, electrons are pulled towards the nucleus, resulting in a smaller radius.

How many isomers does butane have?

Answer

a.

Explanation

Butane (C₄H₁₀) has two structural isomers.

Isomer 1 is the straight chain normal structure for butane (called n-butane) .

Isomer 2 (called 2-methylpropane) is a different structure with a branched chain which has a carbon atom joined onto three other carbon atoms.

In the following diagram, two nails are fixed on a cork and is placed in a beaker. The nails are connected to the two terminals of a battery through a bulb. When a substance X is poured in the beaker the bulb started to glow. What

Answer

c.

Explanation

Glowing of bulb indicates that there is a flow of current through the solution The electric current is carried through the solution by ions. Whereas alcohol and glucose does not conduct electricity.

Since the cation present in acids is H ⁺ , this suggests that acids produce hydrogen ions, H ⁺ (aq) , in solution, which are responsible for their acidic properties.