Question 2 :
The visible universe is estimated to contain $10^{22}$ stars. How many moles of stars are present in the visible universe?

Question 9 :
Give the formulae of the compounds formed from carbon and oxygen.

Question 10 :
Compute the ratio by mass of the combining elements for Aluminium Fluoride.

Question 11 :
An atom with 3 protons and 4 neutrons will have a valency of

Question 13 :
Which of the following correctly represent the electronic distribution in the Mg atom?

Question 14 :
Which of the following is true for an element? (i) Atomic number = number of protons + number of electrons (ii) Mass number = number of protons + number of neutrons (iii) Atomic mass = number of protons = number of neutrons (iv) Atomic number = number of protons = number of electrons.

Question 15 :
Rutherford’s 'alpha ($\alpha$) particles scattering experiment’ resulted in to discovery of _______.

Question 16 :
A truck starts from rest and rolls down a hill with a constant acceleration. It travels a distance of 400 m in 20 s. What is it's acceleration?

Question 18 :
Antibiotics commonly block biochemical pathways important for the growth of ______

Question 22 :
A green plant is carrying out photosynthesis. Is it a work?

Question 24 :
The gravitational potential energy of an object at a point above the ground is defined as the work done in raising it from the ground to that point against gravity.

Question 25 :
The relation connecting the initial velocity $\left(u\right)$ and final velocity $\left(v\right)$ of an object moving with a uniform acceleration a, and the displacement, s is__________.

Question 26 :
An automobile engine propels a 1000 kg car (A) along a levelled road at a speed of $36 kmh^{–1}$.Now, suppose after travelling a distance of 200 m, this car collides with another stationary car (B) of same mass and comes to rest. Let its engine also stop at the same time. Now car (B) starts moving on the same level road without getting its engine started. Find the speed of the car (B) just after the collision.

Question 27 :
It was observed that the atoms of elements, completely filled with 8 electrons in the outermost shell show little chemical activity. TRUE OR FALSE?

Question 28 :
An isotope of cobalt is used in the treatment of cancer.TRUE OR FALSE?

Question 29 :
The number of electrons gained, lost or shared so as to make the octet of electrons in the outermost shell is called?

Question 30 :
If mass number is 24 and number of protons is 12, then find number of electrons.

Question 31 :
If mass number is 2 and number of proton is 1, then find number of neutrons.

Question 32 :
If mass number is 1, number of neutrons is 0, number of protons is 1 and number of electrons is 1 then find atomic number.

Question 33 :
Atomic number is defined as the total number of _______ present in the nucleus of an atom.

Question 34 :
Which one of the following is a correct electronic configuration of sodium?

Question 36 :
An active____________ recruits many cells to the affected tissue to kill off the disease-causing microbes.

Question 37 :
What are the two conditions essential for being free of disease?

Question 38 :
Under which of the following conditions are you most likely to fall sick?

Question 39 :
Any disease that causes poor functioning of some part of the body will affect our health. TRUE or FALSE?