41. What is laughing gas?
A. Nitrous Oxide
B. Carbon monoxide
C. Sulphur dioxide
D. Hydrogen peroxide
42. Actinides are the elements with atomic numbers from
A. 97 to 104
B. 101 to 115
C. 89 to 103
D. 36 from 43
43. The two elements that are frequently used for making transistors are
A. boron and aluminium
B. silicon and germanium
C. iridium and tungsten
D. niobium and columbium
44. The filament of an electric bulb is made of
A. tungsten
B. nichrome
C. graphite
D. iron
45. Diamond is an allotropic form of
A. germanium
B. carbon
C. silicon
D. sulphur