Analyse the given diagram. Recall the changes that occur to the iron nails if they are kept for one week and answer the following questions. Which test tubes had their nails rusted? Which test tubes had the maximum amount of rust in the iron nails kept in them? What are the factors which favour the corrosion of an iron article kept exposed to atmosphere? Which of the iron nails did not rust? What could be the reason?

The iron nails in the three test tubes that contain moist cotton, sodium chloride solution and dilute hydrochloric acid or vinegar will undergo rusting. This is because, in the test tube containing moist cotton, both air and water content is available for rusting. Similarly, in the test tube containing sodium chloride solution, the presence of a salt is there, and in the another test tube, the presence of an acid is there. That is, they are the factors which increase the rate of rusting. The iron nail in the test tube containing moist cotton will have the maximum amount of rust. This is because, in this test tube, both air and water content are available for the iron nail to rust easily. The factors which favour the corrosion of an iron article kept exposed to the atmosphere are: (i) Presence of water vapour in the air. (ii) The oxygen present in the air. The iron nail which is present in the test tube containing quicklime will not rust. This is because, the quicklime absorbs the water vapour present in the surroundings easily.

E M B I B E

Science for Class 8 - Part 1>Chapter 7 - Metals>Exercise 8>Q 1

HARD

8th Kerala Board

IMPORTANT

Earn 100

Iron is a metal used extensively in our daily life. Do the articles made of iron undergo any chemical change over a period of time?

Important Questions on Metals

HARD

8th Kerala Board

IMPORTANT

Science for Class 8 - Part 1>Chapter 7 - Metals>Exercise 8>Q 2

Is it only for the purpose of beautification we paint the iron bars of windows in our houses? What would happen if we do not do so?

MEDIUM

8th Kerala Board

IMPORTANT

Science for Class 8 - Part 1>Chapter 7 - Metals>Exercise 8>Q 3

Do you know the factors which favour the rusting of iron? List them.

HARD

8th Kerala Board

IMPORTANT

Science for Class 8 - Part 1>Chapter 7 - Metals>Exercise 8>Q 4

Question Image

Analyse the given diagram. Recall the changes that occur to the iron nails if they are kept for one week and answer the following questions.

Which test tubes had their nails rusted?
Which test tubes had the maximum amount of rust in the iron nails kept in them?
What are the factors which favour the corrosion of an iron article kept exposed to atmosphere?
Which of the iron nails did not rust? What could be the reason?

HARD

8th Kerala Board

IMPORTANT

Science for Class 8 - Part 1>Chapter 7 - Metals>Exercise 9>Q 1

Why do you think the iron window bars in house close to the sea shore corrode faster?

HARD

8th Kerala Board

IMPORTANT

Science for Class 8 - Part 1>Chapter 7 - Metals>Exercise 9>Q 2

Are there metals which are resistant to corrosion? Which are they? What are their uses?

HARD

8th Kerala Board