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Those substances through which things can be seen, are called transparent. On the other hand there are some materials through which you are not able to see. These materials are called opaque. The materials through which objects can be seen, but not clearly, are known as translucent. We can therefore group materials as opaque, transparent and translucent. Shopkeepers usually prefer to keep eatables in transparent containers of glass or plastic so that buyers can easily see these items. While you cannot tell what is kept in a closed wooden box, a cardboard or a metal container.
Which statement is not true about opaque substances?

A Opaque substances absorb most of the light falling on them.
B We cannot see the objects through opaque substances.
C A mirror is an opaque substance.
D Opaque substances reflect most of the light falling on them.

Certain metals have the capacity to displace some metals from their salt solutions. These reactions are known as metal displacement reactions. A metal placed higher in activity series can displace the metal occupying lower position from aqueous solution of its salt or a more reactive metal can displace less reactive metal from its salt solution.
Take aqueous solution of copper sulphate in one test tube and ferrous sulphate in another test tube. Dip an iron nail in copper sulphate and copper wire in ferrous sulphate solution. Mark the correct observation.

A Blue colour in first test tube changes to light green and green in the second test tube changes to blue.
B There is no reaction in both the test tubes.
C Blue colour in first test tube changes to light green and no change in second test tube.
D Blue colour remains as such and green colour in second test tube changes to blue.

In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as:
Assertion : When the heavier component in a mixture settles after water is added to it, the process is called decantation.
Reason : Sand and water can be separated by churning.

A If both assertion and reason are true and reason is the correct explanation of assertion.
B If both assertion and reason are true but reason is not the correct explanation of assertion.
C If assertion is true but reason is false.
D If assertion is false but reason is true.

You are provided with the following materials
(i) magnifying glass
(ii) mirror
(iii) stainless steel plate
(iv) glass tumbler.
Which of the above materials will you identify as transparent?

A (i) and (ii)
B (i) and (iii)
B (i) and (iv)
C (iii) and (iv)

In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as:
Assertion : Naphthalene balls are kept in open air in order to maintain its state.
Reason : The process of conversion of solid state to liquid is sublimation.

A If both assertion and reason are true and reason is the correct explanation of assertion.
B If both assertion and reason are true but reason is not the correct explanation of assertion.
C If assertion is true but reason is false.
D If assertion is false but reason is true.

The process in which an acid completely reacts with a base to form salt and water is called neutralisation. The salts which are formed may be acidic, basic or neutral. The substances which do not bring any change in the colour of the indicators are called neutral substances.
When sodium hydroxide is added to dilute hydrochloric acid

A sodium chloride salt is formed.
B sodium chloride salt and water are formed.
C sodium chloride salt and water are formed and heat is evolved.
D sodium chloride salt and water are formed and heat is absorbed.

In this section, each question has two matching lists. Choices for the correct combination of elements from List-I and List-II are given as options A, B, C and D out of which one is correct.

Code :
----P---- Q---- R---- S

A 4---- 1---- 2---- 3
B 4---- 3---- 2---- 1
C 3---- 2---- 4---- 1
D 1---- 4---- 3---- 2

Refer to the given flow chart.

Identify P, Q, R and S and select the correct option.

The electron distribution in an aluminium atom is

A 2, 8, 3
B 2, 8, 2
C 8, 2, 3
D 2, 3, 8.

Which of the following statements about Rutherford’s model of atom are correct?
(i) Considered the nucleus as positively charged
(ii) Established that the α–particles are four times as heavy as a hydrogen atom
(iii) Can be compared to solar system
(iv) Was in agreement with Thomson’s model

A (i) and (iii)
B (ii) and (iii)
C (i) and (iv)
D only (i)