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.

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

Answer: B) 3/4 hrs Explanation: Walking at 3/4th of usual rate implies that time taken would be 4/3th of the usual time. In other words, the time taken is 1/3rd more than his usual time   so 1/3rd of the usual time = 15minor usual time = 3 x 15 = 45min = 45/60 hrs = 3/4 hrs.

Answer: D) personal income taxes Explanation: The largest proportion of federal revenues comes from personal income taxes. Almost half of all federal revenue (47 percent) comes from individual income taxes.

Answer: B) 2 Explanation: Given a2 + b2 = c2   Now  1logc+ab  + 1logc-ab    = logbc+a + logbc-a   = logbc2-a2 = 2logbb = 2

Here in the alphabets the letter U is missing and it represents the word MISSING YOU (U).

Answer: B) 182 Explanation: The given series follows a logic that 11 x 12, 12 x 13, 13 x 14, 14 x 15, 15 x 16,... So the missing number is 13 x 14 = 182

Answer: D) Felix Explanation: Here my name "Iron59" means Felix. Since my father is a chemist he gave code Iron for Fe as chemical symbol for Iron is Fe and my mother is a mathematician she gave 59 for Lix as Roman word for 59 is Lix.   Hence my name is FELIX.