Students in a science class observed that when a strip of Magnesium (Mg) metal was placed in a test tube containing Hydrobromic acid (HBr), the Magnesium began to bubble as hydrogen gas and Magnesium Bromide are formed. Which of the following choices show both the correctly balanced equation and identify the type of reaction?

A.

Mg+2HBr →H2+MgBr2 (synthesis)

B.

2Mg+HBr →H2+2MgBr2 (decomposition)

C.

Mg+2HBr →H2+MgBr2 (single replacement)

D.

Mg+2HBr →2H2+MgBr2 (double replacement)

Pls answer correctly I really need a good grade on this

Awater balloon launcher uses an elastic band with a spring constant of 115 n/m to use thee launcher you stretch thee band back with a balloon n it the water balloons have a mass of 1.3 kg a) if you stretch the band by 0.8 m, what elastic force will the band exert? b) with the band stretched 0.8 m, how much elastic potential energy is stored in the spring? c) if you release the band, it pushes forward. what is the kinetic energy of the balloon when it reaches the natural length of the band? d) what is the speed of the balloon when it reaches the natural length of the band?