Structure of Atom Test

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Structure of Atom Test - 39

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Weekly Quiz Competition

Question 1
1 / -0

Maximum number of electrons held in the d orbitals is :

A
$$2$$

B
$$6$$

C
$$8$$

D
$$10$$

E
$$14$$

Solution

Maximum number of electrons held in the d orbitals is 10.
There are 5 sub-levels in a d orbital, each one can have a maximum 2 electrons.
Hence, 5 sub-levels can have a maximum of 10 electrons.
Thus, s, p, d and f orbitals can accommodate a maximum of 2, 6, 10 an 14 electrons.
Question 2
1 / -0

Statement 1: Atoms of different elements can have the same mass number.
Statement 2: The atoms of each element have a characteristic number of protons in the nucleus.

A
Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.

B
Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.

C
Statement 1 is correct but Statement 2 is not correct.

D
Statement 1 is not correct but Statement 2 is correct.

E
Both the Statement 1 and Statement 2 are not correct.
Question 3
1 / -0

Which of the following assumptions made by Neils Bohr regarding the hydrogen atom was NOT new and "radical"?

A
Electrons are only stable in certain orbits

B
Atoms only emit electromagnetic radiation when electrons transition to lower energy states

C
The Coulomb force is responsible for keeping the electron in orbit around the positive nucleus

D
An electron in a hydrogen atom can only orbit the nucleus if its angular momentum is some integer multiple of $$h/2 \pi$$

E
All of the above were new and "radical"

Solution

It is the electromagnetic force, one of the four fundamental forces of nature, theta governs the interaction of electrons with the positively charged nucleus to form an individual atom. The EM force is carried by photons, which serve in the capacity of gauge bosons as they do this force interaction.
Question 4
1 / -0

Who postulated that electrons revolve in orbits around the nucleus?

A
Bohr model

B
deBroglie's wave hypothesis

C
Heisenberg's uncertainty principle

D
Dalton

E
Rutherford

Solution

According to Bohr's model, electrons revolve around the nucleus in fixed energy orbits.
Question 5
1 / -0

According to J.J Thomson's atomic model, negative charges are embedded in:

A
A lump of positive charge

B
A lump of neutral particles

C
A lump of small atoms

D
The nucleus

Solution

The plum pudding model is one of several scientific models of the atom. According to J.J. Thomson atomic model the positive particles in the atom form something like the "batter" in a plum pudding, while the negative electrons are scattered through this "batter".
Question 6
1 / -0

Atoms of different elements having the same mass number are known as :

A
isotopes

B
isobars

C
isotones

D
isomers

Solution

Isobars, are the atoms having the same mass number but different atomic number. For example, the atomic number of carbon and nitrogen is 6 and 7 respectively. Carbon-14 an isotope of carbon has a mass number of 14 which is same as that of nitrogen and hence carbon-14 and nitrogen are isobars.
Question 7
1 / -0

An atom with atomic number $$20$$ is most likely to combine chemically with the atom whose atomic number is___________.

A
$$11$$

B
$$16$$

C
$$18$$

D
$$10$$

Solution

Atomic number $$20$$ will be distributed in electron shell as $$2,8,8,2$$.
Its valency is $$2$$. It will loose this $$2$$ electron to gain stability and noble gas configuration. If atomic number $$11$$ is distributed in electron shell it will be $$2,8,1$$.
Atom with valence electron $$1$$ will loose this atom to gain stability. Hence, both $$_{20}X$$ & $$_{11}X$$ will gain nothing i.e. will not gain stable electronic configuration after combining with each other.
An atom with atomic number $$16$$ has electronic configuration as $$2,8,6$$.It will gain $$2$$ electron from $$_{20}X$$ and complete its octet. Thus atom having atomic number $$20$$ will combine most likely with atom having atomic number $$16$$ as both will gain stable electronic configuration.
Question 8
1 / -0

The value of first Bohr's radius of a hydrogen atom is ________.

A
$$0.529A^o$$

B
$$5.29 \times 10^{-12}$$

C
$$5.29A^o$$

D
none of these

Solution

The radius of $$n^{+n}$$ Bohr orbit is given by,
$$r_n=\dfrac { { n }^{ 2 }{ n }^{ 2 } }{ 4{ \pi }^{ 2 }{ mZe }^{ 2 } } $$
Now, for hydrogen, Ze=1 and
for first orbit, n=1
$$\therefore r_1=\dfrac { { n }^{ 2 } }{ 4{ \pi }^{ 2 }{ me }^{ 2 } } =0.529°$$
Thus, Bohr radius is the mean radius of the orbit of an electron around the nucleus of a hydrogen atom at its ground state.
Question 9
1 / -0

The change in velocity when electron jumps from the first orbit to the second orbit is__________.

A
half of its original velocity

B
twice of its original velocity

C
one fourth of its original velocity

D
equal to its original velocity

Solution

Total Energy of electron, $$E_T =$$ Potential energy (PE) + Kinetic energy (KE)
For an electron revolving in a circular orbit of radius, r around a nucleus of H atom:
$$PE = -Ze^2/r$$
and $$KE = Ze^2/2r$$
Thus ,$$E_T = (-Ze^2/r) + (Ze^2/2r) = -Ze^2/2r=-KE$$
For hyrogen atom: $$E_T=E_n=-R_H(1/n^2)$$
For n=1, $$E_1=-R_H$$ and $$KE_1=\frac{1}{2}mv_1^2$$
For n=2, $$E_2=-R_H/4$$ and $$KE_2=\frac{1}{2}mv_2^2$$
Since $$E_n =-KE$$
thus, $$\dfrac {E_1}{E_2}=\dfrac {KE_1}{KE_2}$$
or $$\dfrac {1}{1/4}=\dfrac {v_1^2}{v_2^2}$$
$$v_2^2=v_1^2/4$$
$$v_2=v_1/2$$
velocity in second orbit is half of the velocity in first orbit.
option A is correct
Question 10
1 / -0

What is the percentage composition of the elements in ammonia?
$$(N = 14, H=1)$$

A
$$N = 82.35%$$%, $$H = 17.65%$$%

B
$$N = 83.35%$$%, $$H = 16.65%$$%

C
$$N = 80.35%$$%, $$H = 19.65%$$%

D
$$N = 81.35%$$%, $$H = 18.65%$$%

Solution

The atomic masses of $$N$$ and $$H$$ are 14 g/mol and 1 g/mol respectively.
The molecular weight of $$ \displaystyle NH_3$$ is $$ \displaystyle 14+3(1)=17$$ g/mol. Thus, 17 g of $$ \displaystyle NH_3$$ will contain 14 g of N and 3 g of H.
The percentage of N in $$ \displaystyle NH_3$$ $$ \displaystyle = \dfrac {14}{17} \times 100=82.35 \% $$
The percentage of H in $$ \displaystyle NH_3$$ $$ \displaystyle =100-82.35=17.65 \% $$

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Structure of Atom Test - 39

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Structure of Atom Test - 39

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Question 1

$$2$$

$$6$$

$$8$$

$$10$$

$$14$$

Solution

Question 2

Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.

Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1.

Statement 1 is correct but Statement 2 is not correct.

Statement 1 is not correct but Statement 2 is correct.

Both the Statement 1 and Statement 2 are not correct.

Question 3

Electrons are only stable in certain orbits

Atoms only emit electromagnetic radiation when electrons transition to lower energy states

The Coulomb force is responsible for keeping the electron in orbit around the positive nucleus

An electron in a hydrogen atom can only orbit the nucleus if its angular momentum is some integer multiple of $$h/2 \pi$$

All of the above were new and "radical"

Solution

Question 4

Bohr model

deBroglie's wave hypothesis

Heisenberg's uncertainty principle

Dalton

Rutherford

Solution

Question 5

A lump of positive charge

A lump of neutral particles

A lump of small atoms

The nucleus

Solution

Question 6

isotopes

isobars

isotones

isomers

Solution

Question 7

$$11$$

$$16$$

$$18$$

$$10$$

Solution

Question 8

$$0.529A^o$$

$$5.29 \times 10^{-12}$$

$$5.29A^o$$

none of these

Solution

Question 9

half of its original velocity

twice of its original velocity

one fourth of its original velocity

equal to its original velocity

Solution

Question 10

$$N = 82.35%$$%, $$H = 17.65%$$%

$$N = 83.35%$$%, $$H = 16.65%$$%

$$N = 80.35%$$%, $$H = 19.65%$$%

$$N = 81.35%$$%, $$H = 18.65%$$%

Solution

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