3.37 x 10¹⁰ molecules
Explanation:
Given parameters:
Volume of water = 1pL = 1 x 10⁻¹²L
Density of water = 1.00g/mL = 1000g/L
Unknown:
Number of water molecules = ?
Solution:
To solve this problem, we first find the mass of the water molecule in the inkjet.
Mass of water = density of water x volume of water
Then, the number of molecules can be determined using the expression below:
number of moles = 
Number of molecules = number of moles x 6.02 x 10²³
Solving:
Mass of water = 1 x 10⁻¹² x 1000 = 1 x 10⁻⁹g
Number of moles:
Molar mass of H₂O = 2 + 16 = 18g/mol
Number of moles = 
= 5.6 x 10⁻¹⁴moles
Number of molecules = 5.6 x 10⁻¹⁴ x 6.02 x 10²³ = 33.7 x 10⁹
= 3.37 x 10¹⁰ molecules
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Right answer is B . Trust me .
Answer:
The Moon weighs about 7.349*10^22 kg
How much does “an elephant” weigh? Grown-up elephants vary between 1.7 tons (small wood elephant cow) and 6 tons (big African elephant bull). Let us pick 2.720 tons or 2720 kg as an average weigh one, this is valid for Asian elephants.
A mole of elephants weighs 6.022 * 10^23 x 2720 kg = 1.638 * 10^27 kg.
That is 1,638 * 10^27 / 7,349*10^22 = 22289 times more.
We will assume that the wave is moving in free space, thus, the velocity of the wave would be equal to the speed of light = 3 * 10^8 meters/sec
The velocity of the wave can be calculated using the following rule:
velocity = frequency * wavelength where:
velocity = 3 * 10^8 m/sec
frequency = 2500 Hz
wavelength is the unknown that we want to calculate.
Substitute with the givens in the above equation to get the wavelength as follows:
3 * 10^8 = 2500*wavelength
wavelength = 120 * 10^3 meters
