Answer : The correct option is, (b) 22.5 M
Explanation : Given,
Mass of calcium nitrate tetrahydrate = 266 g
Molar mass of calcium nitrate tetrahydrate = 236.15 g/mole
Volume of solution = 
Molarity : It is defined as the moles of solute present in one liter of solution.
Formula used :

Now put all the given values in this formula, we get:

As calcium nitrate tetrahydrate dissociate to give 1 mole of calcium ion, 2 moles of nitrate ion and 4 moles of water.
The concentration of nitrate ion = 
Thus, the concentration of nitrate ion is, 22.5 M
Answer is: the absolute pressure of the air in the balloon is 1.015 atm (102.84 kPa).
n = 0.250 mol; amount of substance.
V = 6.23 L; volume of the balloon.
T = 35°C = 308.15 K; temperature.
R = 0.08206 L·atm/mol·K, universal gas constant.
Ideal gas law: p·V = n·R·T.
p = n·R·T / V.
p = 0.250 mol · 0.08206 L·atm/mol·K · 308.15 K / 6.23 L.
p = 1.015 atm; presure of the air.
The answer is 3. The releasing of energy means exothermic reaction. So the ΔH should be negative. And the greatest quantity of energy released means that the greatest number. So according to the table I, the answer is 3.
Answer:
How many 250 mg tablets of metronidazole are needed to make 150 mL of suspension containing
100 mg/mL?
a. 25
b. 30
c.50
d. 60
Explanation:
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The atomic number of an element identifies the number of protons and electrons.