Phytoplankton, a specific type of microscopic producer, supplies up to 50% of Earth's oxygen.
Explanation:
- The rule apply for the multiplication and division is :
The least number of significant figures in any number of the problem determines the number of significant figures in the answer.
- The rule apply for the addition and subtraction is :
The least precise number present after the decimal point determines the number of significant figures in the answer.
a) 12.3 mm × 15.853 mm :
Three significant figures.
b) 72.98 · 15.830 ml
Three significant figures.
c) 12.3 mm + 15.853 mm
Three significant figures.
d) 172.3 cm - 15.853 cm
Four significant figures.
27.6 - 22.3 = 5.3; you simply subtract the old density from the new density.
Answer: A mass of 0.518 g of phenol must be dissolved in 25.0 g of naphthalene to produce a solution that is 0.22 m in phenol.
Explanation:
Given: Mass of naphthalene = 25.0 g
Molality = 0.22 m
This means that 0.22 moles of solute is present per kg of solvent.
As 25.0 g of naphthalene is there that will be 25.0 g per 1000 g (1 kg) is equal to 0.025 kg.
Hence, moles of phenol are calculated as follows.
Also, molar mass of phenol is 94.11 g/mol. This means that 1 mole of phenol contains 94.11 g.
Therefore, mass contained by 0.0055 moles of phenol is as follows.
Thus, we can conclude that a mass of 0.518 g of phenol must be dissolved in 25.0 g of naphthalene to produce a solution that is 0.22 m in phenol.