Structure of Atom Test

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Structure of Atom Test - 64

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Question 1
1 / -0

Radioactivity can be effected by :

A
temperature

B
pressure

C
radiation

D
all of these

Solution

Exposure to very high levels of radiation, such as being close to an atomic blast, can cause acute health effects such as skin burns and acute radiation syndrome (“radiation sickness"). It can also result in long-term health effects such as cancer and cardiovascular disease.
Therefore Radioactivity can be affected by radiation itself.
Hence Option C is the right answer.
Question 2
1 / -0

$$\alpha,\beta$$ and $$\gamma$$ radiations come out of a rodiactive substance

A
when it is heated

B
when put in atomic reactor

C
spontaneously

D
under pressure

Solution

Alpha and beta particles consist of matter, and gamma rays are bursts of energy. The type of radiation emitted depends on the radioactive substance.
An alpha particle is made up of two protons and two neutrons bound together. Beta particles are high energy electrons. Gamma rays are waves of electromagnetic energy or photons.
From this, it is clear that these three radiations come out of a radioactive substance spontaneously.
Hence option c is the right answer.
Question 3
1 / -0

According to the nuclear reaction $$_4 Be + \ _2 He^4 \longrightarrow \ _6 C^{12} + \ _0 n^1$$, mass number of $$(Be)$$ atom is:

A
4

B
9

C
7

D
6

Solution

The sum of atomic masses on the reactant side is equal to the sum of atomic masses on the product side.
Sum of atomic masses of reactants = sum of atomic masses of products
mass number of $$Be+4=12+1$$
mass number of $$Be=13-4=9$$

Hence, option $$B$$ is correct.
Question 4
1 / -0

Nitrogen has the electronic configuration $$1s^2, 2s^2, 2p_x^1, 2p_y^1, 2p_z^1$$ and not $$1s^2, 2s^2, 2p_x^2, 2p_y^1, 2p_z^0$$ which is determined by

A
Aufbau's principle

B
Pauli's exclusion principle

C
Hund's rule

D
Uncertainty principle

Solution

According to Hund's rule, electron pairing in p,d, and f subshells cannot occur unit each orbital of a given subshell contains one electron each or is singly occupied. or if two or more orbitals of equal energy are available, electrons will occupy them singly before filling them in pairs.

Hence , option C is correct .
Question 5
1 / -0

The expression for Bohr's radius of an atom is

A
$$r = \dfrac{n^2h^2}{4\pi^2me^4z^2}$$

B
$$r = \dfrac{n^2h^2}{4\pi^2me^2z}$$

C
$$r = \dfrac{n^2h^2}{4\pi^2me^2z^2}$$

D
$$r = \dfrac{n^2h^2}{4\pi^2m^2e^2z^2}$$

Solution

$$ r = \dfrac{n^{2}h^{2}}{4\pi^{2} e^{2}mZ} $$

Hence, option B is correct.
Question 6
1 / -0

The ratio of the radii of the first three Bohr orbits is:

A
$$1:5:33$$

B
$$1:2:3$$

C
$$1:4:9$$

D
$$1:8:27$$

Solution

$$r_n \propto n^2$$

Option C is correct.
Question 7
1 / -0

The radius of the first Bohr orbit of hydrogen atom is $$r$$. The radius of the $$3^{rd}$$orbit would be:

A
$$3r$$

B
$$9r$$

C
$$27r$$

D
$$none\ of\ these$$

Solution

$$r_n =r_0 \dfrac {n^2}{Z}\Rightarrow r_3 =r(3)^2 =9r \left(A / q, \dfrac {r_0}{Z}=r \right)$$

Option B is correct.
Question 8
1 / -0

If an isotope of hydrogen has two neutrons in its atom, its atomic number and atomic mass number will respectively be:

A
2 and 1

B
3 and 1

C
1 and 1

D
1 and 3

Solution

Tritium is the isotope. It contains 2 proton and 1 nutron.
$$\therefore \text{atomic number} =n_p=2$$
and $$\text {atomic mass} =n_p+n_n=2+1=3$$

Option B is correct.
Question 9
1 / -0

An element $$_{96}X^{227}$$ emits $$4\alpha$$ and $$5\beta$$ particles to form new element Y. Then atomic number and mass number of Y are:

A
93; 211

B
211; 93

C
212; 88

D
88; 211

Solution

$$_{96}X^{227} \rightarrow _aY^b + 4\alpha + 5 \beta$$

On equating mass number:
$$227 = a + 4 \times 4 + 0, \ a = 211$$

On equating atomic number:
$$96 = b + 2 \times 4 - 5, \ b = 93$$

Hence, option A is correct.
Question 10
1 / -0

A radium $$_{88}Ra^{224}$$ isotope, on emission of an $$\alpha$$ -particle gives rise to a new element whose mass number and atomic number will be:

A
220 and 86

B
225 and 87

C
228 and 88

D
224 and 86

Solution

When an $$\alpha$$-particle is emitted by any nucleus than atomic weight decreases by four units and atomic number decreases by two units,

$$_{88}Ra^{224} \xrightarrow []{-\alpha} \ _{86}X^{220}$$.

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Re-Attempt Weekly Quiz Competition

Structure of Atom Test - 64

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Structure of Atom Test - 64

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SHARING IS CARING

Question 1

temperature

pressure

radiation

all of these

Solution

Question 2

when it is heated

when put in atomic reactor

spontaneously

under pressure

Solution

Question 3

4

9

7

6

Solution

Question 4

Aufbau's principle

Pauli's exclusion principle

Hund's rule

Uncertainty principle

Solution

Question 5

$$r = \dfrac{n^2h^2}{4\pi^2me^4z^2}$$

$$r = \dfrac{n^2h^2}{4\pi^2me^2z}$$

$$r = \dfrac{n^2h^2}{4\pi^2me^2z^2}$$

$$r = \dfrac{n^2h^2}{4\pi^2m^2e^2z^2}$$

Solution

Question 6

$$1:5:33$$

$$1:2:3$$

$$1:4:9$$

$$1:8:27$$

Solution

Question 7

$$3r$$

$$9r$$

$$27r$$

$$none\ of\ these$$

Solution

Question 8

2 and 1

3 and 1

1 and 1

1 and 3

Solution

Question 9

93; 211

211; 93

212; 88

88; 211

Solution

Question 10

220 and 86

225 and 87

228 and 88

224 and 86

Solution

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