The first element of each period has 1 valence electron and the last element of each period . . . . . . . . have electrons. (Except helium)

A 2.0 L flask holds 0.40 g of helium gas. If the helium is evacuated into a larger container while the temperature is held constant, what will the effect on the entropy of the helium be?

A

It will remain constant as the number of helium molecules does not change.

B

It will decrease as the gas will be more ordered in the larger flask.

C

It will decrease because the molecules will collide with the sides of the larger flask less often than they did in the smaller flask.

D

It will increase as the gas molecules will be more dispersed in the larger flask.

The process of excitation of an electron from valence band to conduction band leaves an empty hole in the valence band and is called as ____________

A

Detection

B

Absorption

C

Degeneration of an electron-hole pair

D

Regeneration of an electron-hole pair

Find the velocity of an electron when its kinetic energy is equal to one electron volt (in 105m/s). Given charge of an electron e = 1.6 x 10-19 and mass of an electron m = 9.1 x 10-31.

A

3.9

B

4.9

C

5.9

D

6.9

A free electron is a valence electron that has broken away from its parent atom.

A

True

B

False

Except Helium, all noble gases have how many electrons in the outermost shell?

A

4

B

8

C

6

D

10

Consider the following statements in case of reverted gear train: 1. The direction of rotation of the first and the last gear is the same. 2. the direction of rotation of the first and the last gear is opposite. 3. The first and the last gears are on the same shaft. 4. The first and the last gears are on separate but co-axial shafts. Which of these statements is/are correct?

A

1 and 3

B

2 and 3

C

2 and 4

D

4 alone

In the modern periodic table, what are the basic elements of group 18 (Except helium all other than having eight electrons in their outermost orbit)?

A

bimetallic

B

transition element

C

inert gases

D

rare soil elements

Valency of an element depends on which of the following? I. Number of losing electron II. Number of gaining electron III. Number of sharing electron

A

Only I and II

B

Only I and III

C

Only II and III

D

All I, II and III

Is an element used in semiconductors whose atoms have three valence electrons.

A

An acceptor

B

A donor

C

Germanium

D

Silicon

An example of an element whose molecules have three valence electrons?

A

Silicon

B

Copper

C

Germanium

D

Aluminium

The first element of each period has 1 valence electron and the last element of each period . . . . . . . . have electrons. (Except helium)

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