Answer:

Explanation:
Given data

Required
Partial pressure of helium
Solution
First calculate the total volume of gas mixture once the stopcock is opened
So

As temperature remains constant,by Boyle's Law we calculate the partial pressure of the helium gas
So

Answer:
The intensity of laser 2 is 4 times of the intensity of laser 1.
Explanation:
The intensity in terms of electric field is given by :

E is electric field
It means, 
In this problem, lasers 1 and 2 emit light of the same color, and the electric field in the beam of laser 1 is twice as strong as the e-field of laser 2.
Let E is electric field in the beam of laser 1 and E' is the electric field in the beam of laser 2. So,

We have,
E'=2E
So,

So, the intensity of laser 2 is 4 times of the intensity of laser 1.
When you work out it helps clear your thoughts and think of nothing. It makes you feel good.