## How many structure isomers can you draw for pentane?

A. 2 B. 3 C. 4 D. 5 Answer Pentane (C5​H12​) is an organic compound and an alkane with five carbon atoms. Pentane has three structural isomers. These are n-pentane, Iso-pentane and neo-pentane.Pentane means exclusively the n-pentane isomer; the other two being called isopentane (methylbutane) and neopentane (dimethylpropane). Cyclopentane is not an isomer of pentane. Structures of all the three isomers are given here.Option B is correct.

## (Figure 1) Shows Four Charges At The Corners Of A Square

Figure 1) shows four charges at the corners of a square of side L. What magnitude and sign of charge Q will make the force on charge q zero? The vertical forces acting on q are: {eq}F_y = kq(\frac{4Q}{2L^2}\sin{45} – \frac{Q}{L^2}) \\ F_y = kq(\frac{1.414Q}{L^2}-\frac{Q}{L^2}) \\ F_y =…