Answer:
C. An electron has a high probability of being in certain regions.
Explanation:
In the electron cloud model, there are no electron-orbits around the nucleus but a cloud. This cloud has various densities with respect to distance from the nucleus. The most dense region of the cloud (which is the region close to the nucleus) is where electrons has the highest probability of existence.
The model explains that an electron a greater chance of being in the region closer to the nucleus. Thus, an electron has a high probability of being in certain region of the cloud about the central nucleus. And an electrostatic force exists between the nucleus and the electrons.
Answer:
Explanation:
The number of valence electrons tells us the group number of the neutral atom.
The atom has 4 valence electrons.
The atom is in group 4.
Answer:- 3. 
and 
Explanations:- An empirical formula is the simplest whole number ratio of atoms of each element present in the molecule/compound.
For example, the molecular formula of benzene is 
. The ratio of C to H in it is 6:6 that could be simplified to 1:1. So, an empirical formula of benzene is CH.
In the first pair, the ratio of C to H in first molecule is 2:4 that could be simplified to 1:2 and the empirical formula is 
. In second molecule the ratio of C to H is 6:6 and it could be simplified to 1:1. and the empirical formula is CH. Empirical formulas are different for both the molecules of first pair and so it is not the right choice.
In second pair, C to H ratio in first molecule is 1:2, so the empirical formula is . The C to H ratio for second molecule is 1:4, so the empirical formula is 
. Here also, the empirical formulas are not same and hence it is also not the right choice.
In third pair, C to H ratio in first molecule is 1:3, so the empirical formula is . In second molecule the C to H ratio is 2:6 and it is simplified to 1:3. So, the empirical formula for this one is also . Hence. this is the correct choice.
In fourth pair, first molecule empirical formula is CH. Second molecule has 2:4 that is 1:2 mole ratio of C to H and so its empirical formula is . As the empirical formulas are different, it is not the right choice.
So, the only and only correct pair is the third one. 3. and
The largest advantage of sodium-ion batteries is the high natural abundance of sodium. This could make commercial production of sodium-ion batteries less expensive than lithium-ion batteries. As of 2020, sodium ion batteries have very little share of the battery market.
Answer : The rms speed of the molecules in a sample of 
gas at 300 K will be four times larger than the rms speed of 
molecules at the same temperature, and the ratio 
constant with increasing temperature.
Explanation :
Formula used for root mean square speed :
where,
= rms speed of the molecule
R = gas constant
T = temperature
M = molar mass of the gas
At constant temperature, the formula becomes,
And the formula for two gases will be,
Molar mass of = 32 g/mole
Molar mass of = 2 g/mole
Now put all the given values in the above formula, we get
Therefore, the rms speed of the molecules in a sample of gas at 300 K will be four times larger than the rms speed of molecules at the same temperature.
And the ratio constant with increasing temperature because rms speed depends only on the molar mass of the gases at same temperature.
