Tag: structure of atoms

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Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

Number of neutrons present in $1.7$ g of ammonia is:

  1. $0.8N _A$
  2. $0.7N _A$
  3. $0.652N _A$
  4. $0.52N _A$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Let us consider the problem.
For, moles of $N{H _3} = \frac{{1.7}}{{17}} = 0.1$
Let the Neutrons in 1 molecules of $N{H _3} = 7 + 3 \times 0 = 7$
Hence,
Number of Neurons $= 0.1 \times {N _A} \times 7$
The correct answer is $0.7{N _A}$
Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

Calculate number of neutrons present in $12 \times 10^{25}$ atoms of oxygen $( _8O^{17})$:
(Given : N$ _A = 6 \times 10^{23}$)

  1. $1800$
  2. $1600$
  3. $1800\ N _A$
  4. $3200\ N _A$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Atomic number =$ P =8$ 


Atomic Mass =$ N+P=17$


                         $N=9$
 Total no. of Neutrons = $9\times 12\times 10^{25}$

                                     =$\dfrac{9\times 12\times 10^{25}\times N _{A}}{6\times 10^{23}}$ 

                                 $=1800N _{A}$

Hence, the correct option is C.

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

The lightest particle is/are :

  1. electron

  2. proton

  3. neutron
  4. $\beta$-particle
Reveal answer Fill a bubble to check yourself
A,D Correct answer
Explanation
The electron is the lightest particle of the atom. It has a mass of $ 9.1 \times 10^{-28}$ grams. Comparing this mass to that of the proton's at $1.6726 \times 10^{-24}$ grams, an electron is nearly $0.0005$ times the proton's mass.

Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei. Hence, their mass will similar to that of the electron.

Hence, options A and D are correct.
Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms
State whether true or false :

A neutron can be found in all atoms.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The statement, 'Neutron can be found in all atoms' is false.


Neutron is absent in hydrogen atoms. 

The nucleus of $ _1^1H$ contains only a proton. 

So it is not necessary that all atoms have neutron in them.

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

Assertion : Protons are better projectiles than neutrons.
Reason : The neurons being neutral do not experience repulsion from positively charged nucleus.

  1. If both (A) and (R) are correct, and (R) is the correct explanation of (A).

  2. If both (A) and (R) are correct, but (R) is not the correct explanation of (A).

  3. If (A) is correct, but (R) is correct.

  4. If (A) is incorrect, but (R) is correct.

  5. If both (A) and (R) are incorrect.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Neutrons are better projectiles than protons.
The decreasing order of the projectile power is $\displaystyle _0n^1 > _{1}H^{1} > _{1}H^{2}> _{2}He^{4}$
The neurons being neutral do not experience repulsion from positively charged nucleus.
Thus, (A) is incorrect, but (R) is correct.

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

Arrange the following particle in increasing order of values of e/m ratio : electron (e), proton (p), neutron (n) and $\displaystyle \alpha $-particle $\displaystyle (\alpha) $.

  1. n, p, e, $\displaystyle \alpha $
  2. n, $\displaystyle \alpha $, p, e
  3. n, p, $\displaystyle \alpha $, e
  4. e, p, n, $\displaystyle \alpha $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$\displaystyle n< \alpha < p< e$            

e/m of n = 0
$\displaystyle e/m: : of: : \alpha =\frac{9.58\times 10^{4}}{2}c/g$
e/m of p = $\displaystyle 9.58\times 10^{4}: : c/g$
e/m of e = $\displaystyle 1.7588\times 10^{8}: : c/g$

Multiple choice chemistry structure of the atom neutrons discovery of neutrons structure of atoms

Which of the following has the greatest mass?

  1. Electron

  2. Proton

  3. Neutron

  4. Hydrogen cation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Neutron has greatest mass. Proton is a subatomic particle with symbol p and positive electric charge of +1 elementary charge and mass slightly less than that of neutron. Mass of neutron is $1.6749\times10^{-27}  kg$.