Consider the following statements:

1. The number of protons in the nucleus of an atom of a given element is called the atomic number of that element.

2. Mass number of an atom is defined as the sum of number of protons and neutrons present in the nucleus of an atom.

3. Atoms of an element that have the same atomic number (Z) but different mass number (A) are called isotopes.

Which of the above statements is incorrectly stated?

Q.

Fill in the blanks in the following statements :

(a) The number of protons in the nucleus of an atom is called its ....................

(b) The total number of protons and neutrons in the nucleus of an atom is called its ....................

(c) An atom has atomic mass number 23 and atomic number 11. The atom has .................... electrons.

(d) An atom of an element has 11 protons, 11 electrons and 12 neutrons. The atomic mass of the atom is ....................

(e) If the nucleus of an atom has atomic number 17, mass number 37 and there are 17 electrons outside the nucleus, the number of neutrons in it is ....................

(f) Almost all the mass of an atom is concentrated in a small region of space called the ....................

(g) Cathode rays are a beam of fast moving ....................

(h) The anode rays obtained from hydrogen gas consist of particles called ....................

(i) The maximum number of electrons that can be accommodated in L shell are ....................

(j) The maximum number of electrons that can go into the M shell is ....................

(k) The subatomic particle not present in a hydrogen atom is ....................

(l) The electron has .................... charge, the proton has .................... charge, and the neutron has .................... charge.

Q. An atom of an element contains $13$ electrons. Its nucleus has $14$ neutrons. Find out its atomic number and approximate atomic mass. An isotope has atomic mass $2$ units higher. What will be the number of protons, neutrons and electrons in the isotope?

Q. Atomic number is the number of protons present in the nucleus of an atom of an element.

Q. The ratio of the mass of ${}^{12}C$ atom to that of an atom of element= X (whose atomicity is four) is 1:9. The molecular mass element X is:

Q. Assertion :Isobars are the elements having same mass number but different atomic number. Reason: Neutrons and protons are present inside nucleus.