Question

27. The electrons present in the outermost shell are called

(a) Valency electrons (b) Octate electrons (c) Duplet electrons (d) Valence electrons

28. An alpha particle contains

(a) 4 positive charge and 2 mass unit (b) 2 positive charge and 4 mass unit

(c) 2 positive charge and 2 mass unit (d) 4 positive charge and 4 mass unit

29. The atomic number of sodium is 11 and its mass number is 23. It has

(a) 11 neutrons and 12 protons (b) 12 protons and 11 electrons

(c) 11 electrons and 12 neutrons (d) 12 electrons and 11 neutrons

30. The electronic configuration of chlorine is

(a) 2,7 (b) 2,8,8,7 (c) 2,8,7 (d) 2,7,8

31. The isotope used to remove the brain tumours and treatment of cancer is

(a) U-235 (b) Na-24 (c) Iodine (d) C0-60

32. In an alpha scattering experiment, few alpha particles rebounded because

(a) Most of the space in the atom is occupied

(b) Positive charge of the atoms very little space

(c) The mass of the atom is concentrated in the centre

(d) All the positive charge and mass of the atom is concentrated in small volume

33. The atomicity of K2Cr2O7 is

(a) 9 (b) 11 (c) 10 (d) 12

34. The formula for quicklime is

(a) CaCl2 (b) CaCo3 (c) Ca(OH)2 (d) CaO

35. The symbol of cadmium is

(a) Ca (b) Cu (c) Cm (d) Cd

36. All noble gas molecules are

(a) Monoatomic (b) Diatomic (c) Triatomic (d) Both I and II

37. The formula of ethanol is C2H5 – OH. What will be its molecular mass?

(a) 46 u (b) 34 u (c) 34 g (d) 46 g

38. Number of moles present in 28g of nitrogen atoms are

(a) 1 mole (b) 2.3 moles (c) 0.5 mole (d) 2 moles

39. The molecular mass of x is 106. x can be

(a) CaCO3 (b) SO3 (c) Na2CO3 (d) NaCl

40. Which of the following is a wrong Combination?

(a) 6.022 Χ 1023 molecules of oxygen = 32g of oxygen

(b) 6.022 Χ 1023 ions of sodium = 23g of sodium

(c) 6.022 Χ 1023atoms of C = 24g of carbon

(d) 6.022 Χ 1023 atoms of H = 1g of hydrogen atoms

41. What property of an element determines its chemical behaviour?

(a) Size of an element (b) Valency of an element

(c) Molar mass of the element (d) None of these​

Answer 1

Answer:

27.octate electron

30. 2,8,7