Answer:
C
Explanation:
through the desk....here desk is the student's medium to hear the sound. its oblivious because when he lifts his head away from the desk he hears nothing else
Answer:

Explanation:
Given:
- temperature of skin,

- initial temperature of steam vapour,

- latent heat of steam,

- mass of steam,

- specific heat of water,

- final temperature,

<em>Assuming that no heat is lost in the surrounding.</em>
<u>We know:</u>

<u>Now the total heat given by the steam to form water at the given conditions:</u>
..............................(1)
where:
latent heat given out by vapour to form water of 100°C
heat given by water of 100°C to come at 34°C.
putting respective values in eq. (1)



is the heat transferred to the skin.
The charge of the copper nucleus is 29 times the charge of one proton:

the charge of the electron is

and their separation is

The magnitude of the electrostatic force between them is given by:

where

is the Coulomb's constant. If we substitute the numbers, we find (we can ignore the negative sign of the electron charge, since we are interested only in the magnitude of the force)