Tag: structure of the atom

Questions Related to structure of the atom

An atom of each element has a definite combining capacity called : 

chemistry structure of the atom electronic configuration and valency electron configuration periodic trends in physical properties

  1. valency

  2. affinity

  3. bonding

  4. energy levels

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Correct Option: A
Explanation:

An atom of each element has a definite combining capacity called its valency.

For example Na has electronic configuration 2,8,1 
So, valency is 1 as after losing one electron it will have stable octet.

The electrons present in the outermost shell of an atom are known as :

chemistry structure of the atom electronic configuration and valency electron configuration periodic trends in physical properties

  1. protons

  2. neutrons

  3. octet

  4. valence electrons

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Correct Option: D
Explanation:

The electrons present in the outermost shell of an atom are known as valence electrons.

The valency of nitrogen in nitrogen dioxide is:

chemistry structure of the atom electronic configuration and valency electron configuration periodic trends in physical properties

  1. 1

  2. 2

  3. 3

  4. 4

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Correct Option: D
Explanation:

$(D)$  $ 4$


$Sol. $  let the valency of nitrogen in be $ x$. 
           valency of oxygen = $ -2 $
          For $NO _2 $ it will be ,
                                $ x + 2 \times(-2) = 0 $
                                 $ x = +4 $
Hence, the valency of nitrogen in $ NO _2$ is $ +4 $. 

Valency of magnesium and oxygen in $MgO$ is:

chemistry structure of the atom electronic configuration and valency electron configuration periodic trends in physical properties

  1. one and one

  2. two and two

  3. one and two

  4. two and one

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Correct Option: B
Explanation:

Ans. $(B)$ $(two$ $and$ $two)$

This is because magnesium loses two electrons to have an octet and oxygen gains two electrons to have an octet. The final formula of magnesium oxide is ${MgO}$. So, the valencies magnesium and oxygen in $ {MgO}$ are $2$ and $2$ .

The charge on neutrons is :

chemistry structure of the atom discovery of neutrons structure of atoms discovery of subatomic particles

  1. $-1.602\times10^{-19}C$

  2. $1.602\times10^{-19}C$

  3. $0$

  4. None of the above

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Correct Option: C
Explanation:

Neutrons are neutral. 


They do not have any charge. 

They are electrically neutral.

Hence the correct option is C.

Neutron's relative charge is :

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

  1. $-1$

  2. $+1$

  3. $0$

  4. $-2$

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Correct Option: C
Explanation:

Neutron is a neutral particle.

Which of the following statements is false?

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

  1. Proton has a positive charge

  2. Neutron has no charge

  3. Electrons are found in regions of the atom called orbitals

  4. Electrons has a greater mass than the protons

  5. Protons and neutrons form the nucleons of the atom

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Correct Option: D
Explanation:
Electron has less mass. A proton and a neutron have effectively the same mass. A proton (or a neutron) has approximately 1837 times more massive than an electron.

$ _{7}{X}^{15}$ and $ _{8}{Y}^{15}$ differ in

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

  1. Physical properties

  2. Chemical properties

  3. Number of neutrons

  4. Number of nucleons

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Correct Option: C
Explanation:

The option (C) is the correct answer.
$\displaystyle _{7}{X}^{15}$ and $\displaystyle _{8}{Y}^{15}$ differ in number of neutrons.
Number of neutrons for $\displaystyle _{7}{X}^{15} = 15-7=8$
Number of neutrons for $\displaystyle _{8}{Y}^{15}=15*8=7$
Note: Number of neutrons $\displaystyle =$ mass number $\displaystyle -$ atomic number.

Neutrons are present in all atoms except?

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

  1. He

  2. C

  3. H

  4. Ne

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Correct Option: C
Explanation:

The available hydrogen state ${ H } _{ 1 }^{ 1 }$. It is made of 1 electron, 1 proton and no neutrons. All other elements including isotopes of Hydrogen have neutrons.

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

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

  1. $0.8N _A$

  2. $0.7N _A$

  3. $0.652N _A$

  4. $0.52N _A$

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Correct Option: B
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 $0.7{N _A}$