Answer: The correct option is (c). The total pressure doubles.
Solution:
Initially, only 4 moles of oxygen gas were present in the flask.
(
) ( according to Dalton's law of partial pressure)
....(1)
= Total pressure when only oxygen gas was present.
Final total pressure when 4 moles of helium gas were added:

partial pressure of oxygen in the mixture :
Since, the number of moles of oxygen remains the same, the partial pressure of oxygen will also remain the same in the mixture.

= Total pressure of the mixture.
from (1)

On rearranging, we get:

The new total pressure will be twice of initial total pressure.
Answer:
10
Explanation:
I did that already. You got beo
Answer: Molarity increases
Explanation:
Molarity, also known as concentration in moles/dm3 or g/dm3, is calculated by dividing the amount of solute dissolved by the volume of solvent. So, Molarity (c) = amount of solute (n) / volume (v)
i.e c = n/v
Hence, molarity is directly proportional to the amount of solute dissolved, and inversely proportional to the volume of solvent.
Thus, at same volume, any increase in solute amount increases molarity while a decrease will also decreases molarity.
Reaction:

Magnesium is a stronger reducing agent than copper and is thus able to reduce copper(II) oxide.
Products of the reaction: Magnesium oxide and metallic copper.
A calibration curve requires the preparation of a set of known concentrations of CV, which are usually prepared by dieting a stock solution whose concentration is known.