51) Heavy water is known as heavy because it?
(A) is denser than ordinary water
(B) is an oxide of deuterium
(C) has a heavy or bad taste
(D) has a heavier isotope of hydrogen
52) On descending a group in a periodic table, electropositive character of elements?
(C) Remains same
53) In the periodic table on moving from left to right across a period, the metallic character of an element
(C) Increases and then decreases
(D) Remains constant
54) Mendeleev's periodic table is upset by the fact that?
(A) Noble gases do not form compounds
(B) Atomic weight of elements are not always whole numbers
(C) Many elements have several isotopes
(D) Some groups stand divided into two subgroups A and B
55) Most of the known elements are?
(C) Transition metals
(D) Inner transition metals
56) Stainless steel does not rust because?
(A) Nickel present in it does not rust
(B) Iron forms a hard chemical compound with chromium present in it
(C) Chromium and nickel combine with iron
(D) Chromium forms an oxide layer that protects iron from rusting
57) Dynamite was discovered by
(C) Alfred Nobel
58) In fireworks, the green flame is produced because of
59) Fluorocarbons are effective scavenger for ozone due to
(A) Photolytic reaction of O2 producing CI radicals
(B) Photolytic decomposition of O3 producing O2
(C) Photolytic decomposition of O3 into CI and O2
(D) Photolytic production of oxides of nitrogen
60) Detergents are better than soaps because?
(A) They wash clothes better
(B) Absorb the hardness of water
(C) They are less affected by hard water
(D) They are less soapy