Heating a substance causes molecules to speed up and spread slightly further apart, occupying a larger volume that results in a decrease in density. Cooling a substance causes molecules to slow down and get slightly closer together, occupying a smaller volume that results in an increase in density.
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Answer:
This is one of the factors that affects chemical reactions
Temperature:This is because when the temperature is raised energy in form of heat is supplied to the reacting particles and so the rate of reaction is increased.
In a beta emission, the mass number of the daughter nucleus remains unchanged while the atomic number of the daughter nucleus increases by one unit. The following are isotopes produced when the following undergo beta emission;
1) potassium-42 ------> Ca - 42
2) iodine-131 ------------> Xe - 131
3) iron-52 ---------------> Co - 52
4) sodium-24 -----------> Mg -24
The daughter nucleus formed after beta emission is found one place after its parent in the periodic table.
Regarding the stability of the daughter nuclei, a nucleus is unstable if the neutron-proton ratio is less than 1 or greater than 1.5.
Hence, the following daughter nuclei are stable; Ca - 42, Xe - 131, Mg -24.
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Answer:
B. liquid to gas
Explanation:
Matter exists in 3 different states:
- Solid: in solids, particles in the substance are tightly bond to each other through strong intermolecular forces. Therefore, they can only vibrate around their fixed position, but they cannot move freely: as a result, the distance between the particles is the smallest among the 3 states of matter.
- Liquid: in a liquid, particles are able to slide past each other, however there are still intermolecular forces keeping them not too far from each other. As a result, in liquids, particles are on average more distance from each other compared to solids.
- Gas: in a gas, particles are completely free to move, as the intermolecular forces between them are negligible. As a result, in gases, the distance between molecules is the greatest, compared with solids and liquids.
Therefore, the phase changes in which the average distance between molecules increases is:
B. liquid to gas
