The water equivalent of copper calorimeter is 4.5g, the specific heat of copper is$0.09{\text{calg}}^{-1}°{\text{C}}^{-1}$ . Among the following incorrect one is

Given that water equivalent of copper calorie meter is 4.5 g.

Water equivalent = ms in grams

So W = ms = 4.5 g

We know specific heat of copper$=0.09\text{cal/gm°c}$

$\text{m}\times \text{0}\text{.09}=\text{4}\text{.5}\text{g}$

(i)we get mass of calorimeter

$\text{m}=\frac{450}{9}=50\text{g}$

So option (a) is false

(ii) thermal capacity of calorimeter

$\text{H}=\text{ms}=\text{4}\text{.5}{\text{cal°c}}^{-1}$

So option (b) is true

(iii) the heat required to raise the calorimeter by$\text{8°c}$  is

We know

$\text{Q}=\text{ms}\Delta \text{t}$                                $\Delta \text{t}=\text{8}$

$=\text{4}\text{.5}\times \text{8}$                                   $\text{ms}=4.5{\text{cal°c}}^{-1}$

$\text{Q}=\text{36}\text{cal}$

So option (c)is also true

(iv) Heat required to melt 15 g of ice in calorimeter

${\text{Q}}_{\text{total}}=\text{heat}\text{required}\text{to}\text{melt}\text{15g}\text{of}\text{ice}+\text{heat}\text{required}\text{for}\text{calorimeter}\text{to}\text{be}\text{at}\text{0°C}$ $\text{Q}=15\times 80\text{cal}+0=1200\text{cal}$

So option (d) is also true.

So we get only option (a) as incorrect among the given options.