Fossils provide a window in Earth's history by showing us how they existed in the past. They can be dated through several ways and can show us how animals and plants have evolved over millions of years. Also, fossils can help us better understand ancient disasters by the inclusion of elements (such as <span>volcanic ash or dust from major space object impacts) and how they affected the life on earth)</span>
Answer:
true
Explanation
Unbalanced forces can cause an object to change its motion.If an object is at rest and an unbalanced force pushes or pulls the object it will move. Unbalanced forces can also change the speed or direction of an object that is already in motion.
If a substance causes another substance to be oxidized, that substance is an oxidizing agent. Likewise, the substance that is oxidized in an electrochemical reaction is always the reducing agent.
An Oxidizing agent is the one that gets reduced by accepting electrons. It causes oxidation because it makes the other substance lose electrons.
Oxidizing agents also transfer one electronegative atom like oxygen to the other chemical substance. Halogens are an example of oxidizing agents.
A reducing agent is the one that gets oxidized because it loses electrons in a redox reaction. It loses electrons and achieve a higher oxidation state. Lithium is an example of a reducing agent.
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To cool 156 g of water from 42.9 °C to 20.5 °C, 101 g of CF₂Cl₂ are required.
CF₂Cl₂ is a refrigerant. When it is evaporated, it absorbs heat from water, which cools.
<h3>What is evaporation?</h3>
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase.
- Step 1: Calculate the heat released by water.
We will use the following expression.
Qw = c × m × ΔT = (4.184 J/g.°C) × 156 g × (20.5 °C - 42.9 °C)
Qw = -14.6 kJ
where,
- Qw is the heat released by water.
- c is the specific heat of water.
- m is the mass of water.
- ΔT is the change in the temperature of water.
If water releases 14.6 kJ of heat, CF₂Cl₂ absorbs 14.6 kJ of heat (Qr = 14.6 kJ).
- Step 2: Calculate the mass of the refrigerant required.
We will use the following expression.
Qr = ΔH°evap × m
m = Qr/ΔH°evap = 14.6 kJ / (0.144 kJ/g) = 101 g
where,
- Qr is the heat absorbed by the refrigerant.
- ΔH°evap is the heat of vaporization of the refrigerant.
- m is the mass of the refrigerant.
To cool 156 g of water from 42.9 °C to 20.5 °C, 101 g of CF₂Cl₂ are required.
Learn more about evaporation here: brainly.com/question/25310095
