hi frnds........ i have to ask some questions in which i have some ambiguity ,,, regarding physics
... i need proof ful answers ,, i hope you will help me

1 . which of the following is not is not true about sound waves
(a) sound travels faster in steel than in water

(b) Sound is a longitudinal wave

(c)the speed of sound in a gas is not effected by change in pressure

(d) speed of sound is propotional to absolute tempratute

2 . The temprature at which speed of sound becomes double of its value at 50 degree centigrade is

(a) . 919 degree centigrade

b 819 degree centigrade

(c) 1019 degree centigrade

(d) 1292 degree centigrade

(e) none