21. Valence electrons are :
(a) In the closest orbit of the nucleus
(b) In the most distant orbit from the nucleus
(c) In the various orbits around the nucleus
(d) Not associated with a particular atom
22. In a Silicon crystal, the number of covalent bonds a single atom can form is :
(a) 2
(b) 4
(c) 6
(d) 8
23. Consider the following statements regarding Bohr atomic model. (Pick the right one)
1. It introduces the idea of stationary orbit.
2. It assumes that angular momentum of electron is equal to ½(h/2π).
3. It uses planetary model of atom revolving in circular orbit.
(a) 1 & 2
(b) 2 & 3
(c) 1 & 3
(d) 1, 2 & 3
24. Consider the following statements Rutherford’s alpha particle scattering experiment proved that the nucleus
1. Contains massive particles
2. Is a +ve charge center
3. Is quite stable
Which of the statements are correct ?
(a) 1, 2, 3
(b) 1, 2
(c) 2, 3
(d) 1, 3
25. The atomic number of germanium is :
(a) 24
(b) 26
(c) 28
(d) 32
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