chemistry mcqs

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?
(A) Increases
(B) Decreases
(C) Remains same
(D) None

53) In the periodic table on moving from left to right across a period, the metallic character of an element
(A) Increases
(B) Decreases
(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?
(A) Metals
(B) Non-metals
(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
(A) Daimler
(B) Mosely
(C) Alfred Nobel
(D) Freud

58) In fireworks, the green flame is produced because of
(A) Mercury
(B) Sodium
(C) Potassium
(D) Barium

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