The total number of electrons present in 250 ml of water _______$\times {10}^{26}$

Number of molecules in 250 gm of Water= $\frac{6\times {10}^{23}\times 250}{18}$

No. of electrons$=\frac{6\times {10}^{23}\times 250}{18}\times 10$$=0.8365\times {10}^{26}$