Question

The final temperature of the water obtained by mixing equal volumes of water at 2∘C and 4∘C will be:
(a) 2 ∘C
(b) 1 ∘C
(c) 5 ∘C
(d) 3 ∘C

Answer 1

$Let \: T_{1} \:and \: T_{2} \:are \: temperatures\\of \: two \: types \:of \: water$

$and \: V_{1} \:V_{2} \:are \: there \: volumes \\respectively$

$Given \: T_{1} = 2 ^{\degree}C \\T_{2} = 4^{\degree} C \: and \: V_{1} = V_{2} = x$

$Final \: Temperature = T_{final }$

$\boxed { \pink { T_{(Final)} (V_{1} + V_{2} ) = T_{1} V_{1} + T_{2} V_{2} }}$

$\implies T_{(Final)} ( x + x ) = 2 \times x + 4 \times x$

$\implies T_{(Final)} ( 2x ) = 2 x+ 4 x$

$\implies T_{(Final)} = \frac{6x}{2x}$

$\implies T_{(Final)} = 3^{\degree }C$

Therefore.,

$Option \: \green { ( d ) } \: is \: correct.$

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Answer 2

(d) The answer is 3 ∘C