A47.1 g sample of a metal is heated to 99.0°c and then placed in a calorimeter containing 120.0 g of water (c = 4.18 j/g°c) at 21.4°c. the final temperature of the water is 24.5°c. which metal was used?

Answer : The metal used was iron (the specific heat capacity is ).

Explanation :

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

where,

= specific heat of metal = ?

= specific heat of water =

= mass of metal = 47.1 g

= mass of water = 120 g

= final temperature of water =

= initial temperature of metal =

= initial temperature of water =

Now put all the given values in the above formula, we get

Form the value of specific heat of metal, we conclude that the metal used in this was iron.

Therefore, the metal used was iron (the specific heat capacity is ).

Answer : The correct option is, (C) a positive calcium ion and a negative oxygen ion.

Explanation :

Ionic compound : ionic compounds are the compounds which are made up of positively charged cation and the negatively charged anion. The bond form between the cation and anion is known as ionic bond.

For example : NaCl, LiF, NaBr, etc.

In option C, a positive calcium ion combine with a negative oxygen ion to give calcium oxide. So, these two particles can form an ionic bond with each other.

While the other options A, B and D can not form an ionic bond with each other.

Therefore, the correct option is C.