One classic chemistry experiment involves the reaction of hydrochloric acid and magnesium ribbon. a small piece of magnesium ribbon is placed in a test tube and hydrochloric acid is added to cover the magnesium. students observe that the test tube gets hot, a gas (bubbles) is produced, and when a lit match is inserted in the mouth of the test tube, a loud "bark" is heard. this reaction is represented by the equation: mg + 2hcl → mgcl2 + h2 the reaction can be described as both a reaction and a(n) reaction.
a) synthesis; endothermic
b) neutralization; exothermic
c) decomposition; neutralization
d) single replacement; exothermic

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.