Answer:
How do we know what the temperature of the Earth was in the past? - One way to measure past temperatures is to study ice cores. Whenever snow falls, small bubbles filled with atmospheric gases get trapped within it. In some places, so much snow falls that the older layers become buried and compressed into ice, locking away air bubbles in ice sheets and glaciers
What is the relationship between CO2 (carbon dioxide) and temperature on Earth? - When the carbon dioxide concentration goes up, temperature goes up. When the carbon dioxide concentration goes down, temperature goes down.
What is the greenhouse effect? - the trapping of the sun's warmth in a planet's lower atmosphere, due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.
Why are global sea levels rising? - Global warming is causing global mean sea level to rise in two ways. First, glaciers and ice sheets worldwide are melting and adding water to the ocean. Second, the volume of the ocean is expanding as the water warms.
C: Lithium. Before it was 4Li and after the oxidation it turned out to 2Li
Answer : The moles of methane gas could be, 
Solution :
According to the Graham's law, the rate of effusion of gas is inversely proportional to the square root of the molar mass of gas.
or,
![[\frac{(\frac{n_1}{t_1})}{(\frac{n_2}{t_2})}]=\sqrt{\frac{M_2}{M_1}}](https://tex.z-dn.net/?f=%5B%5Cfrac%7B%28%5Cfrac%7Bn_1%7D%7Bt_1%7D%29%7D%7B%28%5Cfrac%7Bn_2%7D%7Bt_2%7D%29%7D%5D%3D%5Csqrt%7B%5Cfrac%7BM_2%7D%7BM_1%7D%7D)
where,
= rate of effusion of fluorine gas
= rate of effusion of methane gas
= moles of fluorine gas = 
= moles of methane gas = ?
= time = 12.3 min (as per question)
= molar mass of fluorine gas = 38 g/mole
= molar mass of methane gas = 16 g/mole
Now put all the given values in the above formula 1, we get:
![[\frac{(\frac{5.13\times 10^{-3}mol}{12.3min})}{(\frac{n_2}{12.3min})}]=\sqrt{\frac{16g/mole}{38g/mole}}](https://tex.z-dn.net/?f=%5B%5Cfrac%7B%28%5Cfrac%7B5.13%5Ctimes%2010%5E%7B-3%7Dmol%7D%7B12.3min%7D%29%7D%7B%28%5Cfrac%7Bn_2%7D%7B12.3min%7D%29%7D%5D%3D%5Csqrt%7B%5Cfrac%7B16g%2Fmole%7D%7B38g%2Fmole%7D%7D)
Therefore, the moles of methane gas could be,
Answer:
( B) They all have their valence electrons in the same type of subshell.
Explanation:
With each period, a new shell is added to the atom.
Further, the groups are classified based on the type of subshell the last electron enters and number of valence electrons.
For all elements of same group, the last electron enters the same type of subshell.
Say, for group 1, last electron enters s orbital and they have 1 valence elctron.
for group 17, last electron enters p orbital and they have 7 valence electrons.
(A) and (D) are wrong because, energy level of the valence electrons is determined by the principle quantum number n and l and not by the type of subshell(only l) they enter.
(C) if the valence electron enters p orbital, then the elements will be placed in the p- block.
Answer: heat
Explanation:
Infrared radiation is popularly known as "heat radiation",[21] but light and electromagnetic waves of any frequency will heat surfaces that absorb them. Infrared light from the Sun accounts for 49%[22] of the heating of Earth, with the rest being caused by visible light that is absorbed then re-radiated at longer wavelengths
