Why does a cloudily track from behind an aero plane flying at a great altitude?

Why does only xenon from stable compounds among the noble gases?

Why the upper surface of wings of an aero plane are made convex upward and lower concave downwards ?

Why does copper not displace hydrogen from acids ?

Why does copper not liberate H_2 gas from dilute mineral acid ?

Why does a solution of ethanol and cyclohexane show positive deviation from Raoult 's law ?

A figher plane flying horizontal at an altitude of 1.5 km with a speed of 720 km/h passed directly overhead an anti-aircraft gun. At what angle from the vertical shoud the gum be fired for the shell with muzzle velocity of 600 m/s to hit the plane ? At what minimum altitude should the pilot fly to avoid being hit ? g= 9.8 m/ s^2

Why a space rocket usually launched from west to east ? Why it is more advantageous to launch rockets in the equatorial plane ?

An aeroplaine is flying horizontal with a constant velocity of 200m/s at height of 2000 m. If a bomb dropped from the plane is to hit the target, find the distance from the target at wich the bomb is released. G= 9.8 m/ s^@