Operators are symbols that we use when performing operations on one or more operands. The primary types of operators in C are arithmetic, logical, relational, conditional, bitwise, and assignment.

Answer: A) AD 622 Explanation: Muhammad had to leave Mecca his birth place where he started preaching and take refuse in Medina, where he was given a warm welcome. This event took place in AD 622 and is known as the year of the Hijira, or migration, which became the first year of the Muslim Calendar.

Answer: B) 400 mts Explanation: Let the length of the 1st train = L mts Speed of 1st train = 48 kmph Now the length of the 2nd train = L/2 mts Speed of 2nd train = 42 kmph Let the length of the bridge = D mts Distance = L + L/2 = 3L/2 Relative speed = 48 + 42 = 90 kmph = 90 x 5/18 = 25 m/s(opposite) Time = 12 sec => 3L/2x25 = 12 => L = 200 mts Now it covers the bridge in 45 sec => distance = D + 200 Time = 45 sec Speed = 48 x5/18 = 40/3 m/s => D + 200/(40/3) = 45 => D = 600 - 200 = 400 mts Hence, the length of the bridge = 400 mts.

The Guidelines of World Health Organization (WHO) was leanched at the 2013 International AIDS Society Conference held in Kuala Laumpur, Malaysia on June 30, 2013. Note: It was aimed to provide new guidance on the diagnosis of human immunodeficiency virus (HIV) infection, the care of people living with HIV and the use of antiretroviral (ARV) drugs for treating and preventing HIV infection.