CHEMISTRY [1 Mark Question Answer]

Define covalent bond Explain with an example.

what do you understand by electrovalent bond? Explain with an example.

The following table shows electronic configuration of elements P, O, R and S. From the list, choose inert gases and give a reason/reasons for your choice:

Element	Electronic configuration
	K L M N
P	2, 8, 2, _
Q	2, _ , _, _,
R	2, 8, 18, 8,
S	2, 8, 8, _

Choose the inert gases from the following list:
H, He, Na, Ne, Au, Ar, K, Kr, Ra, Rn, Xe.

Name a noble gas which has less than 8 electrons in its valence shell. What is the atomic number of this gas?

The table below shows the elements from P to T, such that a pair of elements is an isotope. Identity the pair and give a reason for your choice:

Elements	No. of protons	No. of neutrons	No. of electrons
P	11	12	11
Q	12	12	12
R	11	13	11
S	13	14	13
T	14	14	14

The ratio of isotopes of ³⁵Cl₁₇. and ³⁷Cl₁₇ in natural chlorine is 1: 3. Calculate the fractional atomic mass of chlorine.

State the number of valence electrons in (a) alkali metals and (b) halogens.

(a) Name an element which has one valence electron, but is a non-metal.
(b) Name an element which has two valence electrons, but is a noble gas.

Atomic numbers of elements P, Q, R and S are 1, 2, 7 and 11 respectively. Classify them as metals, non-metals and noble gases.

If elements P, Q , R and S have same number of valence electrons, will they have same kind of chemical properties? Support your answer by one example.

Amongst the electrons revolving around the nucleus, which electrons will (a) determine chemical properties of an element? (b) do not determine chemical properties of an clement? Give a reason for your answer.

Name three most important subatomic particles present in the nucleus of an atom.

Who discovered neutrons?

State Rutherford’s structure of atom.

State two conclusions from Rutherford’s scattering of alpha particles with gold foil.

Whenever a gas is subjected to electric discharge at low pressure, cathode rays and positive rays formed. what does the formation of these rays tell us about the nature of atoms in he gas?

How does the mass of a proton compare with the mass of

Name a gas which produces positive rays which only consists of protons.

Does the mass and charge on positive rays remain same with the change in nature of gas in a discharge tube?

Who discovered positively charged rays?

How many electrons will weigh as much as one atom of hydrogen?

What is an electron State is charge in coulombs.

Name the Indian Sage who first propounded the idea of atom (anu).