1) Answer: A hot pack feels warm when chemicals in it combine.
Explanation: Reactions or process in which heat is released(produced) are known as exothermic reactions or process and those in which the heat is absorbed are known as endothermic reactions or process.
If a beaker feels cools when chemical in it react then it means the chemicals have absorbed the heat energy from its surroundings and so it is an example of an endothermic process.
A hot pack feels warm when chemicals in it combine means the energy is released in the chemical reaction and so it is an example of an exothermic process.
Plants use the sun's energy for photosynthesis which is a process of forming food for the plants. Energy acts as a reactant in this process and so it is an example of endothermic process.
Frying an egg by heating it on a stove is an example of an endothermic process as the heat is required to fry the egg.
So, the only exothermic process is the second one, "A hot pack feels warm when chemicals in it combine."
2) In the given equation, heat is written as a product means the heat is released in the equation and so it is an example of an exothermic reaction.
So, the correct choice is the last one " It is exothermic because energy is released."
Answer:
The volume is 4.13793 L
Explanation:
Density is a quantity that expresses the relationship between the mass and the volume of a body, so it is defined as the quotient between the mass and the volume of a body:
Density is a characteristic property of every body or substance.
The most commonly used units of density are 
or 
for solids, and 
or 
for liquids and gases.
In this case, you know:
- density= 0.87
- mass= 3.6 kg= 3,600 g (being 1 kg=1,000 g)
- volume= ?
Replacing:
Solving:
volume= 4,137.93 mL
Being 1,000 mL=1 L, then volume= 4,137.93 mL= 4.13793 L
<u><em>The volume is 4.13793 L</em></u>
The right answer is 2.
The number of protons contained in a nucleus (called an atomic number) is characteristic of a chemical element. For a given atomic number, the number of neutrons defines different "types" of this element: isotopes. The variation of the number of protons of the nucleus of an atom, during a nuclear reaction for example, causes a change of the element studied.
Answer:
The answer is 5.10
Explanation:
<h3><u>Given</u>;</h3>
<h3>
<u>To </u><u>Find</u>;</h3>
We know that
pH + pOH = 7
pOH = 7 – pH
pOH = 7 – 1.90
pOH = 5.10
Thus, The pOH of the solution is 5.10
Answer:
Forces between similar molecules are said to be <em>cohesive</em> while those between different types of molecules are said to be <em>adhesive</em>.
Water 'beads' due to its strong <em>cohesive</em> forces. The meniscus of water in a glass tube is <em>concave</em> because the <em>adhesive</em> forces are strong.
Explanation:
The water in a tube has stronger adhesive forces between the water and glass molecules, so the cohesive forces between water molecules are weaker. That makes the water 'ascend' through the tube, giving a concave form of the meniscus. Another example is mercury, which is the opposite. In this case, the cohesive forces are stronger than the adhesive ones, thus the meniscus is convex.
