Which of these cannot be decomposed into simpler substances? iodine alcohol methane ethanol?

iodine

Explanation:

A compound is a pure substance that is formed from the combination of two or more elements. Compound can usually be split into smaller constituents by chemical process. Example of a compound is water . Water contains 2 different elements which are hydrogen and oxygen. The water molecule can be split into it constituent elements by hydrolysis. The properties of a compound is usually different from the constituent elements that formed it.

Any substance that contains only one kind of atom is known as an element. An element cannot be broken into simpler substance by a chemical process.  

All other options are compound except for iodine which is an element. Iodine is an element as it contains only one type of atom. Therefore, it cannot be separated,. Methane(CH4), Ethanol and alcohol is a compound that contains two or more element that can possibly be split into it constituent element.

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied