A heater in a hot water tank gives off 20,000 KJ per hour. The initial temperature of 450 kg of water in the tank is 8.0 degrees * C the tank is heated for 90 minutes , determine the final temperature of the water.

The final temperature of the water is 23.92°C.

Explanation:

Given that,

A heater in a hot water tank gives off 20,000 kJ per hour.  

For 1 hour or 60 minutes, heat is 20,000 kJ

For 90 minutes,

Mass, m = 450 kg or 450000 grams

Initial temperature,

We need to find the final temperature of the water. We know that the specific heat capacity of water is 4.186 J/g- °C

Heat is given by :

Hence, the final temperature of the water is 23.92°C.

answer: - 3.) the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

solution: - as per the rules, oxidation number of oxygen in its compounds is -2. the sum of oxidation numbers of all the elements of a molecule or compound is zero.

also, the oxidation number in elemental form is zero.

in no, the oxidation number of o is -2 so the oxidation number of n is +2 so that the sum is zero.

similarly, the oxidation number of c in co is +2 and o is -2.

on product side the oxidation number of n is 0 as it is in the elemental form() .

oxidation number of c in carbon dioxide is +4 as there are two oxygen in it and we know that each oxygen is -2.

so, oxidation number of n is changing from +2 to 0 and the oxidation number of c is changing from +2 to +4.

since nitrogen is reduced and hence no is acting as an oxidizing agent. carbon is oxidized and so co is acting as a reducing agent.

so, the right choice is number 3.)the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

the answer is c i believe