Answer:

Explanation:
The unbalanced nuclear equation is

Let's write X as a nuclear symbol.

The main point to remember in balancing nuclear equations is that the sums of the superscripts and of the subscripts must be the same on each side of the reaction arrow.
Then
235 = 4 + A , so A = 235 - 4 = 231, and
92 = 2 + Z , so Z = 92 - 2 = 90
And your nuclear equation becomes

Element 90 is thorium, so

Answer:
<u>Heating water with an open flame</u>
<u>Explanation:</u>
Remember, we are told in the label that Acetone is a "flammable liquid and vapor." <em>Being flammable means the substance can easily be set on fire</em>, and we would expect an open flame from heating water to trigger an explosion (a disaster) in which the Acetone is set on fire causing life-threatening dangers to the second group of students.
Potassium carbonate<span> (K</span>2CO3<span>) is a white salt, </span>soluble in water<span> (</span>insoluble<span> in ethanol) which forms a strongly alkaline solution. </span>
<u>Explanation:</u>
It is given that polar solutes can be dissolved in polar solvents and non-polar solutes can be dissolved in non-polar solvent.
Alcohol being polar, does not dissolves ionic salt in it.
is a non-polar solvent.
From the given options:
1. NaCl: This is an ionic salt and hence, it will be soluble in water only.
2.
: Iodine gas is a non-polar solute and hence, will be dissolved in non-polar solvent which is 
3. Ethanol: As, it is a polar molecule and is not an ionic salt, therefore it can be soluble in both water and alcohol.
4. Benzene: It is a non-polar molecule and hence, it will be dissolved in 
5.
: Bromine gas is a non-polar solute and hence, will be dissolved in 
6.
: This is an ionic salt and hence, it will be soluble in water only.
7. Toluene: This is a non-polar solute and hence, will be dissolved in 
8.
: This is an ionic salt and hence, it will be soluble in water only.
Correct option C
<span>Tidal power is harnessed by </span><span>building a dam across the mouth of a bay</span>