Answer: B) Elastic Explanation: A sponge is a porous material. Rubber is an elastic material.  Since Rubber is not a Massive or solid and not an inflexible thing, it is elastic.

Answer: B) salivary glands of vertebrates Explanation: Here Homologous Means having the same relation or relative position or structure.  Here in snakes poison is in glands and here salivary glands are in Vertebrates.

Answer: A) Stratification Explanation: Stratification as actually the settling down of sediments with different properties to form layers/strata over years. Stratification especially occurs on the bed of water bodies such as oceans.   Stratified sedimentary rocks are used to study the ecological conditions over previous years/eras.     The other choices like Windstorms, Glacial Ice and Stream water are mediums which sediments are transported.

The shadow zone is the area of the earth from angular distances of 104 to 140 degrees from a given earthquake that does not receive any direct P waves. The shadow zone results from S waves being stopped entirely by the liquid core and P waves being bent (refracted) by the liquid core. There are two types of Shadow zones: one for P waves and one for S waves.   P wave shadows between 104-140 degree, both sides; S wave shadow from 105 of one side to 105 of the other.

Answer: B) 29 yrs Explanation: Total age seven persons = (26 x 7)yearsTotal age of the first three persons and the last three persons are (19 x 3) years and (32 x 3) years respectively.Age of the person sitting in the middle of the row = 26 x 7 - 19 x 3 - 32 x 3 = 182 - 57 - 96 = 29 years.

Answer: A) Rs. 620 Explanation: Let the C.P of one item is Rs. P and that of other is Rs. (7500 - P) According to the data given C.P = S.P => Px(116/100) + (7500-P)x(86/100) = 7500 => 30P = 105000 => P = 3500 Required difference between selling prices = Rs. [(3500/100) x 116] - [(4000/100) x 86] = 4060-3440 = Rs. 620

Answer: A) 600 Explanation: Two men, three women and one child can be selected in ⁴C₂ x ⁶C₃ x ⁵C₁ ways = 600 ways.

Answer: A) the existence of unpaired electrons in the valence shell Explanation: When atoms react they do so in order to reach the lowest energy, which is the most stable. The electrons orbitals will overlap in the way that reduces the energy the most. Orbitals of similar energy will produce the greatest stabilisation.The answer you gave isn't the whole story, it depends what species is reacting with what. The effective nuclear charge on the atom will affect the energy of the valance electrons.   Hence, the reactivity of an atom arises from the existence of unpaired electrons in the valence shell.