chemistry

Question 1

Who was the first person to assign chemical symbols to the different atoms?

Answer 1

Dalton.

Question 2

Define Element

Answer 2

An element is a substance that cannot be broken down into simpler substances by chemical reactions.

Question 3

Define Compound

Answer 3

Is a substance made up by chemically combining two or more elements.
It has different properties from its constituent elements.

Question 4

Who pictured ‘‘PLUM PUDDING’’ model?

Answer 4

J.J.Thomson
the negatively charged electrons scattered in positively charged sponge like substance.

Question 5

The alpha particles are………………………………….

Answer 5

Helium nuclei,composed of two p and two n with a positive charge.

Question 6

Conclusion of Rutherford experiment are ?

Answer 6

The large no of deflected particles led to the conclusion that the atom is mainly empty space.

Question 7

1] Nuclear Radius
2] Atomic Radius

Answer 7

1] 10^-15 m
2] 10^-10 m

Question 8

Importance of the NEUTRONS.

Answer 8

Neutrons are crucial for the stability of the nuclei.
Because without neutrons protons will repel each other and nucleus would fall apart.

Question 9

Define Isotopes

Answer 9

Atoms of the same element with the different numbers of neutrons are called isotopes. Because atomic number is same because it has to be the same element .

• same element with different mass number.

Question 10

Does isotopes has the same chemical properties ?

Answer 10

Yes because different number of neutrons doesn’t make difference how they react so they occupy same place in the periodic table.

Refer pg no 64

Question 11

Does Isotopes affects physical properties?

Answer 11

Yes difference in mass affects physical proprties such as BP & MP.

Question 12

ow to separate the isotopes?

Answer 12

Heavier isotopes move slower hence easy to differentiate.

Question 13

Chlorine isotopes

Answer 13

Cl-35(abundant)
Cl-37

Question 14

The number of protons and neutrons never change in chemical reactions.
true/false ?

1] then which is responsible for the change in the chemical reactions ?

Answer 14

TRUE

1] Electrons

Question 15

Define Ions

Answer 15

Atoms can lose or gain electrons to form ions.

Question 16

Full spectrum

Answer 16

Ranges from low energy radio waves to high energy gamma waves .

Question 17

All electromagnetic waves travel at the same speed .
TRUE/FALSE ?

Answer 17

Red has the highest wavelength.

TRUE, but they have different wavelength.
[different colors of visible light have different wavelength]

Question 18

Define frequency

Answer 18

The number of waves which pass a particular point in 1 s is called frequency.

Question 19

Relation between frequency and wavelength

Answer 19

Inversely proportional .
hence blue light has the higher frequency than the red light.

[where c is the speed of light]

Question 20

Prism produces ……………..

Answer 20

Continuous spectrum

Question 21

Spectrum

Answer 21

Visible light emits infrared radiations,which has longer wavelength than red light,
UV radiations,with shorter wavelength than violet light.
[REFER PG NO 71]

Question 22

1.Absorption of radiation……..

Answer 22

Uses to excite the atoms from lower energy level to higher energy level.
[excited state is unstable ]

Question 23

The energy that electron gives out when it falls into lower levels is in the form of ?

Answer 23

Electromagnetic radiations

Question 24

one packet of energy [quantum] or photon is released for each electron transition. TRUE/FALSE?

Answer 24

TRUE

Question 25

UV photon > Infrared light Photon [energy ]

Answer 25

True

Question 26

The energy of photon is proportional to the ……………………

Answer 26

frequency of the radiations

Question 27

When an atom falls from excited state to the ground state,light of specific frequency v is emitted.

Answer 27

When an atom moves from the ground state to an excited state,light of specific frequency v is absorbed.

Question 28

E = h ν

Answer 28

Refer pg no 72

Question 29

The electron cannot change its energy in continuous way . TRUE/FASLE

Answer 29

TRUE because it can change only in discrete amts.

Question 30

The energy of atom is QUANTIZED.

Answer 30

Refer pg no 72 & 71

Question 31

1]Diffraction………………………..
2]Scattering of electrons………………………….

Answer 31

1] Wave
2]Particle

Question 32

The shape of the orbital depends upon ?

Answer 32

The energy of electron.

Question 33

Higher the energy ………………….

Answer 33

Farther from the nucleus.

Question 34

The transition from n=1 to n =infinite corresponds to

Answer 34

Ionization

Question 35

Energy level converge at

Answer 35

Highers energy

Question 36

There is a increase in successive Ionization energy .
TRUE/FALSE

Answer 36

TRUE