Answer:
Measuring with a ruler and using final volume minus initial volume
Explanation:
You can measure the volume of a geometric object by measuring its sides with a ruler and calculating the volume according to the corresponding formula for each object. For example, for a rectangular prism it would be

You can also measure the volume of an object by measuring how much water it displaces. To do this you have to fill a measuring cylinder with enough water for the object to be completely submerged and take note of the volume. Then, add the object and note again the volume of the water+object. The difference between both is the volume of the object.

The advantage of the second method is that it can be used for objects with irregular shapes as long as they do not float.
There are 34 g of oxygen in the container.
We can use the<em> Ideal Gas Law</em> to solve this problem.
But
, so
and

STP is 0 °C and 1 bar, so

Question A, B, D belongs to scope of physics such as in question A sound under the water travels in form of current and thus these currents are quite lower in deep water where the aquatic animal find stability in comparison to shallow water or near to the water surface where the current is higher.
In question B, speed of sound under the water can be caliberated by the concentration of the ions present in the water and thus higher the concentration greater will the speed of sound.
In C, the current of ocean is higher in summer due to the higher temperature and thus Question A, B, D belongs to scope of physics only C belongs to chemistry asking about the mixing of wastewater in river to increase acidity all relates to pH of water.