Answer:
The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations. According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.
The factors that affect the rate of a reaction are:
- <em>nature of the reactant</em> - when reactants with different chemical composition are exposed to same conditions they would react differently. For instance, when an acid or base is added on litmus paper, blue litmus paper turns red in presence of acid while red litmus paper turns blue when base is added.
- <em>surface area</em>- a compound with small pieces spread over a large area will react faster than a big lump of a compound occupying a small area.
- <em>temperature of reaction</em>- reactants would react faster at high temperatures. this is because they have higher kinetic energy to collide with each other. Hence a plate of food on the table spoils faster than a plate of food in the fridge.
- <em>concentration</em>- an increase in concentration leads to more molecules available to collide and form products. An example, when you add more of indicator in a solution, the color becomes more clear since more particles react to give more color.
- <em>presence of a catalyst</em>- a catalyst lowers the activation energy, which means less energy is required to shift reaction in forward direction. In the presence of iron (Fe) a catalyst, nitrogen N₂ and hydrogen H₂ react to produce NH₃
The question is incomplete. Complete question is:
Which list represents the classification of the
elements nitrogen, neon, magnesium, and
silicon, respectively?
(1) metal, metalloid, nonmetal, noble gas
(2) nonmetal, noble gas, metal, metalloid
(3) nonmetal, metalloid, noble gas, metal
(4) noble gas, metal, metalloid, nonmetal
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Answer: The correct answer is option 2) nonmetal, noble gas, metal, metalloid
Reason:
1) Non-metal are bad conductors of electricity. Also non-metal are electronegative in nature. Hence, among the provided elements, nitrogen satisfied the criteria. Hence, it is a non-metal.
2) Noble gas are the elements which have completely filled outermost shell. Hence, among the provided elements, Neon satisfied the criteria.
3) Metal are good conductors of electricity. Also metal are electropositive in nature. Hence, among the provided elements, magnesium satisfied the criteria. Hence, it is a metal.
4) Metalloid have conductivity better than non-metals but poor than conductors. Hence, among the provided elements, Silicon satisfied the criteria. Hence, it is a metalloid.
Answers:
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1) [D]: " CO₂ " .
<u>Note:</u><u> </u> This is the only answer choice given that is composed of: "at least two different elements" .
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2) [D]: "carbon and hydrogen" {"C" and "H" .} .
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