Structure of an Atom

Q.

1 fermi equal to _____ meter

Q.

What is the smallest thing in the universe?

Q. If Avogadro's number is $6\times {10}^{23}$ then the number of protons, neutrons and electrons in 14 g of ${}_6{C}^{14}$ are respectively

1. $36\times {10}^{23},48\times {10}^{23},36\times {10}^{23}$
   
2. $36\times {10}^{23},36\times {10}^{23},36\times {10}^{21}$
   
3. $48\times {10}^{23},36\times {10}^{23},48\times {10}^{21}$
   
4. $48\times {10}^{23},48\times {10}^{23},36\times {10}^{21}$

Q.

Rutherford’s experiment on scattering of $\alpha$ - particles showed for the first time that the atom has

1. electrons

2. protons

3. neutrons

4. nucleus

Q.

Name the particles which are present in the nucleus of an atom.

Q. How many electrons, protons and neutrons are there in a nucleus of atomic number $11$ and mass number $24$?
(i) number of electron $=$ ________.
(ii) number of protons $=$ ________.
(iii) number of neutrons $=$ _______.

Q.

Why are electrons important in an atom?

Q. In an atomic solid with BCC arrangement of atoms, the atomic radius of the host atom is 270 pm. A guest atom of largest size is present at one of the faces without disturbing original unit cell dimensions. If Coordinates of the centre of this guest atom are (a/2, a/4, 0 ), where a is the side length of unit cell, radius of the guest atom is closest to A) 180 pm B) 135 pm C) 78.57 pm D) 57.5 pm

Q.

The SI unit of radioactivity is ______.

1. Rd

2. N

3. Bq

4. R

Q. Write all four quantum numbers for the 19th electron of chromium

Q.

Calculate the number of atoms present in 5.6 g of iron(Fe).

Q.

Who discovered Neutrons?

Q.

$\mathrm{\alpha }$-particles are :

1. Negative charged particles

2. Positive charged particles

3. Beam of neutrons

4. Gamma radiation

Q.

Mention two possible source of background radiations.

Q.

Which is the cause of damage referred to as relative biological effectiveness?

1. High temperature

2. Low temperature

3. Pollution

4. Radiation

Q.

Is radical and valency are same? How charges are given on any element or compound?

Q.

Which of the following is the correct representation of electrons, protons and neutrons respectively?

1. ${}_1^{0}e{,}_1^{-1}p{,}_0^{1}n$

2. ${}_{-1}^{0}e{,}_1^{1}p{,}_0^{1}n$

3. ${}_0^{1}e{,}_1^{1}p{,}_1^{1}n$

4. ${}_0^{1}e{,}_1^{1}p{,}_1^{0}n$

Q. UV rays are non-ionising type and are lethal because they damage:

1. Proteins
2. Pigments
3. Nucleic acids
4. All of the above.

Q.

What are the different ways for an atom to attain stability?

Q.

According to Rutherford's atomic model, electrons revolve around the nucles. (True/False)

1. True

2. False

Q. Atoms achieve stable configuration by ____

1. creating required electrons.
2. pairing electrons with protons.
3. losing or gaining electrons.
4. destroying extra electrons.

Q. The phenomenon of radioactivity was discovered in 1896 by _________.

1. Henry Becquerel
2. J.J Thomson
3. John Dalton
4. James Chadwick

Q. Why do only some atoms like uranium undergo nuclear fission????

Q.

The distinction between atoms and molecules was made by ________.

Q.

If Avogadro's number is $6\times {10}^{23}$, then the number of protons, neutrons and electrons in 14 g of ${}_6{C}^{14}$ are respectively:

1. $36\times {10}^{23},36\times {10}^{23},36\times {10}^{21}$

2. $48\times {10}^{23},36\times {10}^{23},48\times {10}^{21}$

3. $48\times {10}^{23},48\times {10}^{23},36\times {10}^{21}$

4. $36\times {10}^{23},48\times {10}^{23},36\times {10}^{23}$

Q.

Who formulated the equation $E=m{c}^2$, i.e. the popular mass-energy equivalence relation?

1. Einstein

2. Fermi

3. Tesla

4. Rutherford

Q.

The element selenium has the symbol ${}_{34}{}^{79}\mathrm{Se}$.Calculate the number of each subatomic particles in selenide anion Se^2-

Q.

Explain:

Nucleus of an atom carries positive charge.

Q.

Name three isotopes of hydrogen, give their symbols, number of protons and number of neutrons.

Q.

What is meant by background radiation?