4x = -12
First, divide both sides by 4. / Your problem should look like:
Second, since 4 goes into 3 to get 12, simplify it by 3. / Your problem should look like:

Answer:
x = -3
Answer is: no reaction occurs.
No reaction occurs because magnesium (Mg) is less reactive than sodium (Na). Sodium is higher in activity series of metals and can not be reduced. <span> Metal X will replace another metal Y in a solution if X is higher in the activity series. </span>
Answer:
A. Peroxide breaking down into water and oxygen
Explanation:
Generally when it comes to changes, there are physical and chemical changes. In physical changes, there are no new substances been formed, however in chemical change new substances are formed.
A. Peroxide breaking down into water and oxygen
This is a chemical change.
B
. Bubbles forming when a pot of water is heated
This is a physical change
C. A pair of jeans soaked in water drying after hanging outside
This is a physical change
D
. A block of ice decreasing in size due to a change in temperature
This is a physical change.
Only option A is different from the rest,hence this is the answer.
Answer:
Work = 90.65 j
Explanation:
Given data:
Mass = 0.500 Kg
Distance = 18.5 m
Work done = ?
Solution:
Work = force . distance
Force = mg
Work = mg.distance
Work = mgh
Work = 0.500 Kg × 9.8 m/s²× 18.5 m
Work = 90.65 Kg .m²/s²
Kg .m²/s² = j
Work = 90.65 j
Answer is A-photosystem II