Explore topic-wise InterviewSolutions in Current Affairs.

• The electrons possess negligible mass. They do not contribute much to the mass of an atom.
• Therefore, the entire mass of an atom is supposed to be present in the nucleus which consists of protons and neutrons, which are collectively called as nucleons.

Hence,

Approximate atomic mass in Daltons is numerically equal to the number of nucleons in the atom.

The mass of a neutron is 1.676 x 10^-24 g

Answer is Same

X-rays < UV rays < Micro wave < Radio

Correct option is  C) 7

The charge of a proton is +1.602 x 10^-19C

(i) ³⁵₁₇Cl

(ii) ²³³₉₂U

(iii) ⁹₄Be

The mass of a proton is 1.676 x 10^-27 kg or 1.676 x 10^-31 g

From Millikan’s experiment, the charge of an electron (e) is -1.602 x 10^-19C.

Mass, m = 1kg

Height, h = 5m

Gravitational potential energy = mgh

= 1 × 10 × 5 = 50J

Let a boy of mass m climb up through a vertical height h either through staircase of using a lift. The force of gravity on the boy is F = mg acting vertically downwards and the displacement in the direction opposite to force (i.e., vertical) is S = −h. Therefore the work done by the force of gravity on the boy is

W = FS = − mgh

or, the work W = mgh is done by the boy against the force of gravity.

Mass of water, m = 50kg

Height, h = 15m

Gravitational potential energy = mgh

= 50 × 10 × 15

= 7500 J

1. Human genome.project (HGP)

2. Application – They can study all the genes in a genome.

Future challenge – Requires expertise and creativity of thousands of scientists of various disciplines.

3. Name the methods involved in it:

• Expressed Sequence Tags (ESTs) 
• Sequence Annotation

We could prepare soft idly as a result of chemical change named fermentation takes place in the idly batter. During fermentation the idly batter undergoes a chemical change by bacteria.

Mass of man = 50kg

Height of ladder, h₂ = 10m

(i) Work done by man = mgh₂

= 50 × 9.8 × 10 = 4900J

(ii) increase in his potential energy:

Height,h₂ = 10m

Reference point is ground, h₁ = 0m

Gravitational potential energy = Mg (h₂-h₁)

= 50 × 9.8 × (10-0)

= 50 × 9.8 × 10 = 4900J

1. Semi conservative DNA replication

2. Meselson and Stahl 

3. Medium containing ¹⁵NH₄Cl and normal ¹⁴NH₄Cl. CsCl used for centrifugation.

According to Thomson’s experiment, e/m ratio for an electron is 1.76 x 108cg^-1.

F = 150N

(a) Work done by the force in moving the block 5m along the slope = Force x displacement in the direction of force = 150 × 5 =750 J

(b) The potential energy gained by the block

U = mgh where h = 3m

= 200 × 3 = 600 J

(c) The difference i.e., 150 J energy is used in doing work against friction between the block and the slope, which will appear as heat energy.

Electrons are filled in an atom according to increasing energies of atomic orbitals. Eg Z=36 eg, is 1s² ,2s² ,2p⁶ ,3s² ,3p⁶ ,4s² ,3d¹⁰,4p⁶ .

Mass, m = 1kg

Velocity, v = 10m/s

Kinetic energy = 1/2 × mass ×(velocity)²

= 1/2 ×1 ×(10)²= 1/2 ×1 ×100

= 50J

If the speed is halved (keeping the mass same), the kinetic energy decreases, it becomes one-fourth (since kinetic energy is proportional to the square of velocity).

John Dalton, a British teacher in 1808 first proposed a firm scientific basis known as Dalton’s atomic theory.

1.Principal Quantum Numbers (n) 

2.Azimuthal Quantum Numbers(l) 

3.Magnetic Quantum Numbers (m) 

4.Spin Quantum Numbers(s)

Mass number on the left side above the symbol and atomic number on the left side below the symbol. 

Eg. Sodium atom can be represented as 23Na₁₁

Electron, proton and neutron.

Correct option is  D) all of these

Answer is Neutrons

No. of protons and electrons

i. Trusteeship

ii. Social Responsibility

iii. Consumers

iv. Investors

v. Business Ethics

vi. Business

vii. Government

viii. Society

The total number of protons and neutrons in an atom is called the mass number it is represented by the Letter ‘A’.

The total number of protons in an atom is called atomic number it is represented as Z.

Rutherford found that most of the alpha particles passed through the gold foil without any deflection and that shows most of the space in the atom is empty.

Answer is Electrons

Complete the table providing details related to these atoms.

 KE= ½ mv² put the values & calculate V(m = 9.1 x 10^-31 Kg) 

V= 812 m/s 

Wave length = h/mv 

= 8967 A⁰

There are equal no. of positive and negative particles in an atom, so it is neutral as a whole.

The number of protons and electrons are equal in an atom.

1.6 x 10^-19 Coulombs. 

The number of positively charged particles (protons) in the nucleus are equal to the number of negatively charged particles (electrons) outside the nucleus. There for can atom is neutral.

The fundamental particles present in an atom are: 

1. Positively charged particles called protons (p) 

2. The negatively charged particles called electrons (e) and. 

3. neutral particles called neutrons (n)

Protons and neutrons

1. Atomic number : The number of protons present in the nucleus of an atom is known as atomic number. It is denoted by ‘Z’ 

2. Atomic mass number : The total number of protons and neutrons present in the nucleus of an the atom is known as mass number. It is denoted by A. Generally atomic number and mass number of the atom of an element is represented by a symbol ZXA. ‘X’ is an element.

The fundamental particle not present in a normal hydrogen atom is neutron.

Neutron is electrically neutral i.e. it has no charge as an electron or a proton has.