Waves will have the highest speed in
air at 0°c
air at 5°c
air at 20°c
air at 30°c

The correct answer is "air at 30 degree centigrade".

Explanation:

Wave is a disturbance or energy carried out from one particle to another.

The kinetic energy is directly proportional to the temperature. The speed of the particle is more at high temperature. Then, the kinetic energy will be more at high temperature. Waves will travel with the highest speed.

Therefore, waves will have the highest speed in air at 30 degree centigrade.

two charges are fixed in place on the x-axis as shown. the charge at x = 0 is negative and has magnitude q = 2 μcoulombs (1 μcoulomb = 10-6 coulombs). the charge at x = d, (d = +12 cm), is positive and has magnitude q = 4 μcoulombs. find a point x = xo along the x-axis at which the electric field is zero.

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min