<h2>Answer : Option B) Hydrogen</h2><h3>Explanation :</h3>
All fossil fuels contains hydrocarbons in it. Amongst the given options hydrogen is the correct answer. Except that it contains carbon in it. Hydrocarbons are those class of compounds which contains hydrogen and carbon as element in it.
They are considered to be good fuels because they naturally bring out complete combustion as they contain hydrogen and carbon in its compound form.
Answer:
24.09 grams of chlorine gas reacted.
Explanation:
Moles of sodium chloride = 
According to reaction, 2 moles of NaCl are formed from 1 mole chlorine gas.
Then 0.6786 moles of NaCl will be formed from;
Mass of 0.3393 moles of chlorine gas:
0.3393 mol × 71 g/mol = 24.09 g
24.09 grams of chlorine gas reacted.
We know that the element Z = 119 would be placed right below the Fr, in the column of the alcaline metals.
We also know that the trend in the electronegativity is to decrease when you go up-down ia group.
The known electronegativities of the elements of this group are:
Li: 0.98
Na: 0.93
K: 0.82
Rb: 0.82
Cs: 0.79
Fr: 0.70
Then the hypotetical element Z = 119 would probably have an electronegativity slightly below 0.70, for sure in the range 0.60 - 0.70.
C. The number of Valence electrons,
Every atom tries to follow the Octet rule i.e To have 8 electrons in its Valence shell.
Every atom tries to accomodate 8 electrons in its Valence shell to stabilize themselves, Metals usually have 1-3 eletrons in their Valence shell which they donate to non metals so their Valnce shell has 8 electroons, (The previous will now be the Valence shell and it will be full)
Similarly Non metals have 4-7 electrons, they accept electrons from metals so they can have 8 electrons in their Valence shell.
Noble gases already have 8 electrons in their Valance shell, so they do not react and stable.
Hope it helps :)
Answer: CaCO3 reaction.
Explanation: CaO and combine together to result in the formation of calcium carbonate compound. we know it is a synthesis reaction.so we can conclude that the most likely products of Cao + co2 → CaCO3 reaction.
