Answer:
9
Explanation:
mass number = protons + neutrons
= 4 + 5 = 9
Answer: The density of lead will be 
Explanation:
Density is defined as the mass contained per unit volume.

Given : Mass of lead=
Volume of lead =
Putting in the values we get:

Thus density of lead will be 
Answer:
1. The graph where x axis and y axis are present is called coordinate.
4. 18
Answer:
100Jkg/°C
Explanation:
Given parameters:
Mass of metal = 2kg
Amount of heat energy = 1600J
Initial temperature = 5°C
Final temperature = 13°C
Unknown:
Specific heat capacity of the metal = ?
Solution:
Specific heat capacity of a body is the amount of heat needed to raise the temperature of unit mass of a body by 1°C.
H = m x C x (T₂ - T₁ )
H is the amount of heat
m is the mass
C is the unknown specific heat capacity
T is the temperature
Insert the parameters and solve;
1600 = 2 x C x (13 - 5)
1600 = 16C
C = 100Jkg/°C