Answer: B) 138 Explanation: The gram formula mass of a compound is nothing but the molar mass. The molar mass of K2CO3 (Potassium Carbonate) is given by Atomic weights of individual elements are   K (Potassium) = 39 g C (Carbon) = 12 g O (Oxygen) = 16 g   Hence, that of K2CO3 = 39(2) + 12 + 16(3) = 78 + 12 + 48 = 138.

Answer: C) 9 : 10 Explanation: The ratio of X and Y ages at present is 4:5.  Then, the ratio 20 years ago will not be more than the ratio at present. So, from the options 9:10 is not satifying => its ratio is 0.9 which is greater than presnt ratio of 0.8.

Answer: D) 120 Explanation: In given word OLIVER there are 3 vowels E, I & O. These can be arranged in only one way as dictionary order E, I & O.   There are 6 letters in thegiven word.   First arrange 3 vowels.   This can be done in 6C3 ways and that too in only one way.(dictionary order E, I & O)   Remaining 3 letters can be placed in 3 places = 3! ways   Total number of possible ways of arranging letters of OLIVER = 3! x C36 ways = 6x5x4 = 120 ways.

Answer: B) Rs. 480 Explanation: Let the sum be Rs. P. Then,   P1+252x1002-P= 510   P[982- 1] = 510.   Sum = Rs. 1920   So, S.I. = (1920 x 25 x 2) / (2 x 100) = Rs. 480

Answer: A) 1134 Explanation: 13 x ? + 47 x 114 x 539 = 31100 x 2000? = 378 x 3? = 1134

Answer: A) Theory Explanation: 'Hypothesis' is a word that gives a brief explanation of the concepts based on the limited evidence. The word 'theory' is closest in meaning to it.

Answer: D) All the above Explanation:    1) SO2                  2) CH2Cl2                3) PCl3 How to check the given molecules are polar or non polar : If the electronegativity of the two bonded atoms are different then the bond is polar. Although, some molecules contain polar bonds, the molecule may be non-polar. If the polarity of all the bonds present in the molecule are cancel each other then molecule is non-polar.   In the given options, SO2  is polar because the dipole moments on the O do not cancel. PCl3  is polar because the P-Cl bonds do not cancel out. CH2Cl2  polar because the C-Cl bonds do not cancel.   Hence, in brief, Polar molecules are molecules with net dipole due to the presence of partial positive and partial negative charge. For example, water is a polar molecule that has partial positive and partial negative charge on it. CO2 is a non polar compound.   Therefore, all the given options SO2, CH2Cl2 and PCl3 are Polar molecules.

Answer: A) 25 Explanation: This can be easily simplified by Approximation process Given 39.96% of 649.85 ÷13.07 = 45.14 - ? can be written as  40% of 650 ÷13 = 45 - ?   40 x 65010013 = 45 - ?? = 45 - 20? = 25.