For very large numbers, it is much more convenient to use scientific notation. To do this, detect first the position of the decimal point. For whole numbers, the decimal point is place implicitly after the very last digit. Then, move this decimal point to the left until you reach to the last digit. In this case, you moved 8 places until you reach 6.4. Because the number is more than 1, the exponent would have a positive sign. Hence, the scientific notation would be 6.4×10⁸.
Answer:
B. 214.02
Explanation:
1 mol of water weighs 18.015 gm and contains 6.023 × 10²³ molecules
From question, We have 7.15 × 10²⁴ molecules
Dividing we get (7.15 × 10 ²⁴) ÷ ( 6.023 × 10²³) = 11.871 molecules
Now, Weight of water = 11.871 × 18.015 = 213.85 which is nearer to option B
<u>Answer:</u> The mass of sucrose required is 69.08 g
<u>Explanation:</u>
To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

Or,

where,
= osmotic pressure of the solution = 8.80 atm
i = Van't hoff factor = 1 (for non-electrolytes)
Mass of solute (sucrose) = ?
Molar mass of sucrose = 342.3 g/mol
Volume of solution = 564 mL (Density of water = 1 g/mL)
R = Gas constant = 
T = Temperature of the solution = 290 K
Putting values in above equation, we get:

Hence, the mass of sucrose required is 69.08 g
The fraction of gas phase molecules is calculated by the division of final pressure to the initial pressure.
Fraction =
(1)
Here, initial pressure = 1.0 atm
final pressure = 
First, convert torr into atm
1 atm = 760 torr
final pressure = 
= 
Now, put the value of initial and final pressure in formula (1)
Fraction =
=
Thus, fraction of the gas phase molecules =
