Answer: Boyle's law
Explanation: It states that pressure of a gas is inversely proportional to the volume of a gas at constant temperature.
∝
at constant temperature
or If the pressure of gas is decreased, the volume increases if the temperature is unchanged and If the pressure of gas is increased, the volume decreases if the temperature is unchanged.

Ultrasound is sound or vibrations, having an ultrasonic frequency, particularly as used in medical imaging. Ultrasound is more commonly used in medical terminology than in industry. Infrasound is sound waves with frequencies below the lower limit of human audibility.
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Answer:
47.2 g
Explanation:
Let's consider the following double displacement reaction.
3 FeCl₂ + 2 Na₃PO₄ → Fe₃(PO₄)₂ + 6 NaCl
The molar mass of Fe₃(PO₄)₂ is 357.48 g/mol. The moles corresponding to 44.3 g are:
44.3 g × (1 mol / 357.48 g) = 0.124 mol
The molar ratio of Fe₃(PO₄)₂ to FeCl₂ is 1:3. The moles of FeCl₂ are:
3 × 0.124 mol = 0.372 mol
The molar mass of FeCl₂ is 126.75 g/mol. The mass of FeCl₂ is:
0.372 mol × (126.75 g/mol) = 47.2 g