Avagadro's law gives the relationship between volume of gas and number of moles of the gas. When the temperature and pressure are constant, volume is directly proportional to number of moles of gas.

V -volume and n - number of moles of gas.
parameters for the first instance are on the left side and parameters for the second instance are on the right side of the equation
initial number of moles n1 - N
n2 - 2N as the number of moles are doubled
V1 - initial volume - 2.10 L
V2 - final volume - V
substituting the values in the equation

V = 4.20 L
final volume is 4.20 L
Answer:
I know that the 100-mL graduated cylinders are always read to 1 decimal place.
I think for 50 mL graduated cylinders, it lets you measure volumes up to 50.0 mL to the nearest 0.1 or 0.2 mL, depending on your exact cylinder.
Answer:
D. Because we cannot easily detect them.
Explanation:
Dark matter are called dark because using existing astronomical instruments we are blinded to them. Dark matter and dark energy are difficult to detect and properly observe. As we know that the whole universe is made up of matter, some of the matter do not interact with the electromagnetic radiations which makes undetectable.
Answer:
2. Volcanoes
Explanation:
The interior of some planets (e.g earth) contains some hot flowing fluids called lava which has a very high thermal energy. The lava as a means of escaping the confinement within the planet, burst out by creating an opening through the ground to the surface of the planet to release the energy (lava).
This process in which the energy is released to the surface of the planet is termed volcanic eruptions. Which occurs majorly in some susceptible regions of the earth.
The openings in the ground that release energy from deep inside the planet is thus called volcanoes.
26. B
27. D
28. C
Hope this helped ☺️