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

Question 97

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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

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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 precipitatereaction 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 is.

AgNO₃+NaCl AgCl + NaNO₃

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

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