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Number of alpha particles N scattered at an angle θ during Rutherford's alpha scattering experiment is :

Oxidation state of hydrogen in H₂O and H₂O₂ respectively is:

Electron can be extracted easily from which of the following elements?

How can we separate a mixture of sulphur and sugar?

The bottom of a lake does not freeze in harsh winter even when the surface is all frozen. Why?

Tritium emissioninvolves which of the following:?

Name the sub-atomic particle whose charge is :

(a) $+1$ (b) $-1$ (c) $0$ .

why a wooden table should be called a solid

Name the temperature at which:

(a) a liquid changes into a gas (b) a solid changes into a liquid

Which of the following is an example of a mixture ?

A solid melts its temperature remains constant explain

In double displacement reactions _______ are exchanged by the reactants.

Question 6
What happens when calcium is treated with water?

(i) It does not react with water.
(ii) It reacts violently with water.
(iii) It reacts less violently with water.
(iv) Bubbles of hydrogen gas formed stick to the surface of calcium.

a) (i) and (iv) (b) (ii) and (iii)

(c) (i) and (ii) (d) (iii) and (iv)

Name a bacterium responsible for fixing atmospheric nitrogen. [1 MARK]

Which of the following statement is true?

If an electron revolves in its orbit of radius 5 x 10^-11 m with a linear velocity of 6.5 x 10⁴ m/s then magnetic field at the center of the hydrogen atom due to the electron is

$H_{3}B{O}_3$ is

Differentiate between:-

Fractional distillation & distillation

Which of the acid is required for the laboratory preparation of nitric acid?

Which of these metals displace hydrogen from dilute acids with explosive violence?

Explain the difference between 2N and $N_2$.

The first model of an atom was given by:

(a) What do we call those particles which have more or fewer electrons than the normal atoms?
(b) What do we call those particles which have more electrons than the normal atoms?
(c) What do we call those particles which have fewer electrons than the normal atoms?

The material which is added to water during purification process at the water works so as to disinfect it is :

(a) potassium permanganate (b) betadine (c) chlorine (d) potash alum

The number of protons in the nucleus of an atom is called it’s....................

On a hot sunny day,why do we feel pleasant sitting under a tree?

What if we drink liquid nitrogen?

Boiling point of a liquid on hill station like shimla is lower than that in delhi . Why

Why acetone evaporate faster than water of same amount?

Biogas mainly consists of:

What are the difference between particles and atoms?

2.5 l of a gas at 9×10⁵ N m⁻² pressure is allowed to contract till the pressure becomes 1.5 × 10⁶ N m⁻². Temperature remaining constant during this process, the volume of the gas is reduced by

Anion O^- is isoelectronic with:

A solution contains $x$ ml of ethyl alcohol mixed with 100ml of water. The concentration of the solution is 28.6% in terms of volume by volume percentage. Find $x$.

Which of the following sub atomic particle do you think will have no electrical charge and mass equal to the mass of hydrogen atom.

Matter is

Which of the following is a correct relationship betwen Kelvin scale and Celsius scale?

Acid rain is formed, when pH of rain water is less than ___ .