IGCSE Chemistry Paper-1: Specimen Questions with Answers 77 - 78 of 99

Question 77

Question

MCQ▾

A solution of NaOH was taken in a test tube and phenolphthalein was added to it. The solution turned pink by doing so. Now HCl is added to it and the pink colour disappeared.

What reaction possibly would have taken place?

Adding Dilute HCl to NaOH

Choices

Choice (4)

a.

Double displacement

b.

Reduction

c.

Decomposition

d.

Neutralization

Answer

d.

Explanation

A neutralization reaction is when an acid and a base react to form water and a salt and involves the combination of H + ions and OH- ions to generate water. The neutralization of a strong acid and strong base has a pH equal to 7.

This experiment shows that the addition of HCl destroys the alkaline nature of NaOH. On the other hand the addition of NaOH solution destroys the acidic nature of HCl. i.e.. both NaOH and HCl appear to cancel the effect of each other.

Question 78

Question

MCQ▾

A metal X exhibits following properties. Which possible metal can be X

  • It is found in free state in nature.
  • It is a very less reactive metal.
  • It does not corrode easily.

Choices

Choice (4)

a.

Iron

b.

Gold

c.

Aluminium

d.

Magnesium

Answer

b.

Explanation

Noble Metals are found as pure metals because they are unreactive and don՚t combine with other elements to form compounds. Because they are so unreactive, they don՚t corrode easily. This makes them ideal for jewellery and coins. Noble metals include copper, palladium, silver, platinum, and gold.

Metals from Top to Down

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