Help answer these questions please! You only have to answer the first one unless it’s already been answered then answer the next one (if you could explain how you did it, it would be much appreciated :))

1a: Lead atoms are heavier than aluminum atoms, which means that a given mass of lead contains fewer atoms than the same mass of aluminum. Since the heat required to raise the temperature depends on the number of atoms, it takes less heat to raise the temperature of the lead than the temperature of the aluminum.

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

the entire statement is true and correct.  

there's no diagram, nothing is illustrated, and no question is asked.