Answer: 68
Explanation:
Isotopes of an element have same number of protons but different number of neutrons. Which means isotopes of an element have same atomic number but different mass number.
Atomic number is equal to the number of protons or the number of electrons for a neutral atom and is specific to a particular element.
Mass number is the sum of number of protons and the number of neutrons.
Given : atomic number of element Q = 68 = number of protons
Mass number of isotope Q-136 = 136
But as isotopes have same atomic number, the number of protons will be same and hence there are 68 protons are in a neutral atom of this isotope.
Molar mass NaCl = 58 g
Mass of solute = 29 g
number of moles: mass of solute / molar mass
n = 29 / 58
n = 0.5 moles
hope this helps!
Given data: <span>molar mass = 180.2 g/mol in 920.0 ml of water at 25 °c.
</span><span>the vapor pressure of pure water at 25 °c is 23.76 mm hg.
</span>Asked: <span>the vapor pressure of a solution made by dissolving 109 grams of glucose
</span><span>
Solution:
moles glucose = 109 g/ 180.2 g/mol=0.605
mass water = 920 mL x 1 g/mL = 920 g
moles water = 920 g/ 18.02 g/mol=51.1
mole fraction water = 51.1 / 51.1 + 0.605 =0.988
vapor pressure solution = 0.988 x 23.76 = 23.47 mm Hg</span>
As the volume of the confined gas decreases at the constant temperature, the pressure exerted by the gas increases.
