Which of the following statements regarding the properly of hard water is/are correct?

1. Temporary hardness of water is due to the presence of soluble magnesium and calcium hydrogen carbonate.
2. Temporary hardness of water can be removed by boiling.
3. Calgon's method is applied to remove temporary hardness of water.
4. Permanent hardness of water is removed by Clark's method.

Select the correct answer using the code given below:

• 1 and 2 only

• 1, 2 and 3

• 3 and 4

• 2 only

An ant is moving on thin (negligible thickness) circular wire. How many coordinates do you require to completely describe the motion of the ant?

• One

• Two

• Three

• Zero

Specific gravity of silver is 11 and specific gravity of iron is 8. Which one among the following is the approximate relative density of silver with respect to iron?

• 1.4

• 0.7

• 3.0

• 2.8

Examine these two statements carefully and select the answers to these items using the codes given below

Statement I: Insolation is greatest when the sun is directly overhead and the sun's rays are vertical.

Statement II: When the sun is lower in the sky, the same amount of solar energy spreads over a greater area of ground surface, so insolation is lower.

• Both the statements are individually true and Statement II is the correct explanation of Statement I

• Both the statements are individually true but Statement II is not the correct explanation of Statement I

• Statement I istrue but Statement II is false

• Statement I is false but Statement II is true

45.

Examine these two statements carefully and select the answers to these items using the codes given below

Statement I: Hard water does not give lather with soap.

Statement II: Calcium and magnesium salts present in hard water form precipitate with soap.

• Both the statements are individually true and Statement II is the correct explanation of Statement I

• Both the statements are individually true but Statement II is not the correct explanation of Statement I

• Statement I is true but Statement II is false

• Statement I is false but Statement II is true

Examine these two statements carefully and select the answers to these items using the codes given below

Statement I: Evapotranspiration helps in classifying the climatic types.

Statement II: Only temperature affects evapotranspiration, hence it can be used for classifying the climatic types.

• Both the statements are individually true and Statement II is the correct explanation of Statement I

• Both the statements are individually true but Statement II is not the correct explanation of Statement I

• Statement I is true but Statement II is false

• Statement I is false but Statement II is true

Sun emits energy in the form of electromagnetic radiation. The following help in the generation of solar energy. Arrange them in the rgnt sequence beginning from the starting of the cycle:

1. Hydrogen is converted to helium at very high temperatures and pressures.
2. The energy finds its way to sun's surface.
3. A vast quantity of energy is generated by nuclear fusion.

Select the correct answer using the code given below.

• 1-2-3

• 2-3-1

• 3-2-1

• 1-3-2

The spread in colours in a rainbow on sky is primarily due to

• dispersion of sunlight

• reflection of sunlight

• refraction of sunlight

• total internal reflection of sunlight

Examine these two statements carefully and select the answer.

Statement I : Glass is not considered as a true compound.

Statement II : Glass does not have a definite melting point.

• Both the statements are individually true and Statement II is the correct explanation of Statement I

• Both the Statements are individually true but Statement II is not the correct explanation of Statement I.

• Statement I is true but Statement II is false.

• Statement I is false but Statement II is true.

Examine these two statements carefully and select the answer.

Statement I : Limestone decomposes when it is heated in air.

Statement II : Increase in the content of CO₂ in the atmosphere in recent years is mainly due to the using of limestone in the manufacture of cement.

• Both the statements are individually true and Statement II is the correct explanation of Statement I

• Both the Statements are individually true but Statement II is not the correct explanation of Statement I.

• Statement I is true but Statement II is false.

• Statement I is false but Statement II is true.