IGCSE Chemistry Paper-1: Specimen Questions with Answers 97 - 98 of 99

Question 97

Question

MCQ▾

ph of some solutions is given in below table. What would be the nature of the substance.

PH of Solutions is Given in Table
S. No.SolutionApp pH value
1Coffee4.5 - 5.5
2Soapy water12
3Saliva6.5 – 7.5
4Battery acid0

Choices

Choice (4)

a.

1- Basic, 2- Neutral, 3 – Neutral, 4 – Acidic

b.

1- Basic, 2- Acidic, 3 – Neutral, 4 -Acidic

c.

1- Acidic, 2- Basic, 3 – Neutral, 4 -Acidic

d.

1- Basic, 2- Neutral, 3 – Neutral, 4 -Basic

Answer

c.

Explanation

pH is a numeric scale used to specify the acidity or alkalinity of an aqueous solution Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are alkaline or basic. Pure water is neutral, being neither an acid nor a base. Contrary to popular belief, the pH value can be less than 0 or greater than 14 for very strong acids and bases respectively.

Question 98

Question

MCQ▾

Which of the following is a precipitation reaction?

Choices

Choice (4)

a.

AgNO3 + NaCl AgCl + NaNO3

b.

Zn + CuSO4 + ZnSO4 + Cu

c.

HCl + NaOH NaCl + H2O

d.

Question does not provide sufficient data or is vague

Answer

a.

Explanation

A precipitate is a solid that forms out of solution. A common example is that of the mixing of two clear solutions: (1) silver nitrate (AgNO3) and (2) sodium chloride (NaCl) : The reaction is.

AgNO3 + NaCl AgCl + NaNO3

The precipitate forms because the solid (AgCl) is insoluble in water.

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