Which reaction is exothermic? ch4 + 2o2 mc016-1.jpg co2 + 2h2o + 891 kj nh4no3 + h2o + 25 kj mc016-2.jpg nh4+(aq) + no3-(aq) 2h2o + 286 kj mc016-3.jpg 2h2 + o2 n2 + o2 + 181 kj mc016-4.jpg 2no

Option (a) is the correct answer.

Explanation:

Exothermic reactions are the reactions in which heat is released. Whereas when there is absorption of heat then the reaction is known as endothermic reaction.

Thus, out of the given chemical equations, the equation [tex]CH_{4} + 2O_{2} \rightarrow CO_{2} + 2H_{2}O + 891 KJ shows that energy has been released. Therefore, this reaction equation is exothermic.

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.

explanation:

venn diagram is pictorial representation with of circles showing the relation between two finite sets or things. the intersection part of two circles conveys the relation present in between those sets or things.

here in the venn diagram of sand and salt two circles represent sand and salt. but the area falling under the intersection of these circle represents the mixture of sand and salt.

so, in a venn diagram the mixture will be placed in a middle that is in between the intersection of two circles.