Hi, the question has some missing part. The complete question should be " If the $pK_{a}$ of $HCHO_{2}$ is 3.74 and the pH of an $HCHO_{2}/NaCHO_{2}$ solution is 3.89, it means that -

(a) $[HCHO_{2}]=[NaCHO_{2}]$

(b) $[HCHO_{2}]> [NaCHO_{2}]$

(c) $[HCHO_{2}]< [NaCHO_{2}]$

Which of the options are true?"

Answer: Option (c) is true.

Explanation:

$HCHO_{2}/NaCHO_{2}$ is an weak acid-conjugate base buffer. Hence, in accordance with Henderson-Hasselbalch equation-

$pH=pK_{a}(HCHO_{2})+log(\frac{[CHO_{2}^{-}]}{[HCHO_{2}]})$

Here, pH = 3.89, $pK_{a}$ of $HCHO_{2}$ = 3.74

So, $3.89=3.74+log(\frac{[CHO_{2}^{-}]}{[HCHO_{2}]})$

or, $\frac{[CHO_{2}^{-}]}{[HCHO_{2}]}$ = 1.41 (>1)

So, $[CHO_{2}^{-}]> [HCHO_{2}]$

or, $[NaCHO_{2}]> [HCHO_{2}]$

Hence, option (c) is correct.

6 0

4 years ago

One atom of an element A =6.644 *10^-23 gm. calculate the no. of gram atom in 80 kg of it.<br><br>

Oksana_A [137]

Answer:

5.3152*10^-24

Explanation:

3 0

4 years ago

Which of the following is the first stage of the photo-independent reaction?

AVprozaik [17]

Carbon source is the answer for ur question

8 0

3 years ago