Number of molecules in 1 dm³ Oxygen = 2.71 x 10²²
<h3>Further explanation</h3>
Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure). At STP, Vm is 22.4 liters/mol.
The mole is the number of particles contained in a substance
1 mol = 6.02.10²³
1 dm³ of oxygen = 1 L Oxygen

n=mol=0.045
No = 6.02.10²³

The Big Bang probably occurred.
~30,000 B.C. North America Asian hunter-gatherers had crossed over the frozen Bering Strait to become first humans in North America.
~10,000 B.C. South America Those who crossed over on Bering Strait into North America had traveled as far south as Argentina by this point.
~6,000 B.C. Europe End of land bridge between Britain and continental Europe. Britain becomes an island.
~4,500 B.C. Brittany (France) The megalithic structures of Carnac were built.
~3,500 B.C. Wales Pentre Ifan is built.
~3,200 B.C. Ireland The Newgrange tomb is built.
Answer : The number of moles of water will be, 1.235 moles
Solution : Given,
Mass of
= 42 grams
Molar mass of
= 34 g/mole
First we have to calculate the moles of 

Now we have to calculate the moles of water.
The balanced chemical reaction will be,

From the balanced reaction, we conclude that
As, 2 moles of
decomposes to give 2 moles of water
So, 1.235 moles of
decomposes to give 1.235 moles of water
Therefore, the number of moles of water will be, 1.235 moles
b is fastest, having the lowest activation energy (35 kJ) and is an exothermic reaction, releasing energy in the form of heat
c is slowest, having the highest activation energy (55 kJ) and is an endothermic reaction, taking in energy from its surroundings
Answer:
14.57g
Explanation:
Given parameters:
Mass of dish + ball = 15.6g
Initial volume of water in the cylinder = 26.7mL
Final volume of water in the cylinder = 38.9mL
Mass of dish = ?
Unknown
Mass of the ball = ?
Solution;
Since the mass of ball and dish is 15.6g,
Mass of the ball =Mass of ball + dish - mass of the dish
Insert the parameters and solve;
Mass of the ball = 15.6g - 1.03g = 14.57g