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3 years ago

Which substance can not be broken down by a chemical change? silicon propane ethane water

Chemistry

2 answers:

babunello [35]3 years ago

5 0

I think the answer is silicon :))

navik [9.2K]3 years ago

5 0

Answer:

$\huge \boxed{\mathrm{silicon}}$

Explanation:

Silicon cannot be broken down by any physical or chemical methods, because it is an element. It has properties of an element nor a compound or mixture.

Silicon is a chemical element with the symbol Si and atomic number 14.

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eduard

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5 0

3 years ago

Francium is the most reactive element in Group 1.

natali 33 [55]

Answer:

Francium is hypothesized to be the most reactive metal, but so little of it exists or can be synthesized, and the longest half-life of its most abundant isotope is 22.00 minutes, so that its reactivity cannot be determined experimentally.

Explanation:

Francium is an alkali metal in group 1/IA. All alkali metals have one valence electron. As you go down the group, the number of electron energy levels increases – lithium has two, sodium has three, etc..., as indicated by the period number. The result is that the outermost electron gets further from the nucleus. The attraction from the positive nucleus to the negative electron is less. This makes it easier to remove the electron and makes the atom more reactive.

Experimentally speaking, cesium (caesium) is the most reactive metal.

6 0

4 years ago

Read 2 more answers

Consider the following reaction at equilibrium. 2CO2 (g) 2CO (g) + O2 (g) H° = -514 kJ Le Châtelier's principle predicts that th

tiny-mole [99]

Answer:

C. at low temperature and low pressure.

Explanation:

Le Châtelier's principle states that when there is an dynamic equilibrium, and this equilibrium is disturbed by an external factor, the equilibrium will be shifted in the direction that can cancel the effect of the external factor to reattain the equilibrium.

For the reaction:

2CO₂(g) ⇄ 2CO(g) + O₂(g), ΔH = -514 kJ.

Effect of pressure:

When there is an increase in pressure, the equilibrium will shift towards the side with fewer moles of gas of the reaction. And when there is a decrease in pressure, the equilibrium will shift towards the side with more moles of gas of the reaction.

The reactants side (left) has 2.0 moles of gases and the products side (right) has 3.0 moles of gases.

So, decreasing the pressure will shift the reaction to the side with higher no. of moles of gas (right side, products), so the equilibrium partial pressure of CO (g) can be maximized at low pressure.

Effect of temperature:

The reaction is exothermic because the sign of ΔH is (negative).

So, we can write the reaction as:

2CO₂(g) ⇄ 2CO(g) + O₂(g) + heat.

Decreasing the temperature will decrease the concentration of the products side, so the reaction will be shifted to the right side to suppress the decrease in the temperature, so the equilibrium partial pressure of CO (g) can be maximized at low temperature.

So, the right choice is:

C. at low temperature and low pressure.

7 0

4 years ago

Which solid from the data table would float on water?

puteri [66]

Answer:

Ther answerr is A only solid A.

Explanation:

The density of water is 1 g/cm3 so anything above that will sink, but as you can see solid A dosnt ev en reach one./ so It will float on water. the other two are over 1 g/cm3.

<h2>If this answer helped mark it brainliest. :)</h2>

5 0

3 years ago

Help please? :)

Ratling [72]

the sand is more likely to be hot because it is on land and the sun can be very hot so i think it would heat the sand. but water is less likely to be heated because its water. and the sun's heat on it would still affect it yes, but not as much as sand

4 0

3 years ago