IGCSE Chemistry: Specimen Questions with Answers 167 - 170 of 240

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Question 167

Write in Short

Short Answer▾

All metal nitrates decompose when heated. A few form a nitrite and oxygen. Most form the metal oxide, oxygen and a brown gas called nitrogen dioxide.

Complete the equation for the action of heat on lead (II) nitrate.

Explanation

Question 168

Question

MCQ▾

Mineral acids in their pure form are ________ in nature.

Choices

Choice (4)

a.

tasty

b.

bitter

c.

corrosive

d.

soothing

Answer

c.

Explanation

Mineral acids in their pure form are ‘corrosive’ in nature. It corrodes surfaces and churns our skins if dropped on our body.

Question 169

Question

MCQ▾

In which equation is the underlined substance acting as a reducing agent?

Choices

Choice (4)

a.

b.

c.

d.

Answer

c.

Explanation

Correct Answer is A i.e.. reducing agent is the substance which itself oxidize and reduce other so carbon mono oxide oxidizes to form carbon di-oxide and reduce . In other reaction the underline substance is acting as oxidizing agent.

Question 170

Question

MCQ▾

What information can we gather about the elements present in a group of the modern periodic table when the group number is provided?

Choices

Choice (4)

a.

Valency of the elements

b.

All the other options

c.

Similar chemical properties

d.

Number of valence electrons

Answer

b.

Explanation

In the modern periodic table, group number denotes the number of valence electrons present in that group.

As number of valence electrons is known so we can determine the valency of the elements.

As chemical properties of an element depend on the number of valence electrons so we can say that the elements present along a group have similar chemical properties.

For example, elements present in group have electrons in their valence shell.

So the valency of the elements is , i.e.. 1.

As elements of group VIIA have valence electrons so they exhibit similar chemical properties.

Hence all the given choices are correct.

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