1.For each of the following sentences, determine whether or not it is a valid proposition, and why: a.He always wears a coat when it’s raining.

b.Sheldon Cooper is a student at UiA.

c.x2 + 5 =9

d.A proposition is called a tautology if it is always false.

e.They are not studying mathematics.

f.Ernst Sundt is the Rector of Noroff University College.

g.There are exactly 20 days in February.

h.The difference of two primes.

i.9 * 3 = 18

j.Where is the nearest Starbucks?