Science Question Answer (1 Marks)

The total number of electrons in a nitrogen atom is 7. Find the number of valence electrons in it.

All the gases form cathode rays and anode rays when electricity is passed through them:
What does the formation of anode rays tell us about the atoms?

What are isotopes? Explain by giving an example.

What is a neutron? State its relative mass and charge.

Which part of an atom was discovered by Rutherford’s alpha particle scattering experiment?

Explain why, the atomic masses of many elements are in fractions and not whole numbers.

The atomic number of an element X is 16.
Write down the electronic configuration of X.

Name the scientist who discovered the nucleus of atom.

Write the distribution of electrons in an atom of element whose atomic number is 18. What is special about the outermost electron shell (or valence shell) of the atom of this element?

What do we call this number which is characteristic of a particular element?

What is the relationship between an atom containing 11 protons, 11 electrons ad 11 neutrons, and another atom containing 11 protons, 11 electrons and 12 neurtrons?

What are valence electrons? Where are valence electrons situated in an atom?

Name the particles used by Rutherford in his experiment on the discovery of nucleus. Also state the charge on these particles.

Name the scientist who discovered electron.

What is the number of valence electrons in the atoms of an element having atomic number 13? Name the valence shell of this atom.

An element has an atomic number 12. How many electrons will be present in the K, L and M energy shells of its atom?

What is the nucleus of an atom and what is the nature of charge on it?

What name is given to those isotopes which have unstable nuclei and emit various types of radiations?

What is the reason for the different atomic masses of the isotopes of an element?

Which of the following are isotopes and which are isobars?
Argon, Deuterium, Calcium, Tritium, Protium.

What conclusion is obtained from the fact that all the gases form cathode rays?

What is the absolute mass and charge of an electron?

What is the general name of the elements having 8 electrons in the valence shell of their atoms?

Name the gas which produces anode rays consisting of protons in the discharge tube experiment.

Name the central part of an atom where protons and neutrons are held together.

All the gases form cathode rays and anode rays when electricity is passed through them:
What does the formation of cathode rays tell us about the atoms?

For the symbols H, D and T, write the subatomic particles (protons, neutrons and electrons) found in each one of them.

What is the relation between the atomic number and mass number of an element?

If an element M has mass number 24 and atomic number 12, how many neutrons does its atom contain?

Which of the nuclear particles is present in the same fixed number in the atoms of any particular element?

Compare an electron, a proton and a neutron in respect of their relative masses and charges.

What is the maximum number of electrons which can be accommodated in the:
Innermost shell of an atom?

Name the particles which actually determine the mass of an atom.

Give one similarity and one difference between a pair of isotopes.

Given that the percentage abundance of the isotope is 90% and that of the isotope is 10%, calculate the average atomic mass of neon.

Which radioactive isotope is used to determine the activity of thyroid gland?

Give one example of a radioactive isotope which is used as a fuel in the reactors of nuclear power plants.

Which noble gas has less than 8 electrons in the valence shell of its atom? What is this number?

The number of protons, neutrons and electrons in particles A to E are given below:

Particle	Protons	Neutrons	Electrons
A	17	18	17
B	3	4	2
C	18	22	18
D	17	20	17
E	9	10	10

Give reasons, find a pair of isotopes from the above particles.

State one use of radioactive isotopes in medicine.

What name is given to those atoms which contain the same number of protons and electrons but different number of neutrons?

Name the scientists who described the arrangement of electrons in an atom.

What is the electronic configuration of a hydrogen atom?

Compare a proton and a neutron in respect of mass and charge.

Name the radioactive isotope which is used in the treatment of cancer.