1. an alpha particle
gamma rays are formally massless, positrons and electrons (beta particles) have negligible mass, but alpha particles have about 4 amu of mass
Answer: Mercury-194 is an unstable isotope and hence is radioactive.
Explanation: Mercury-194 is an isotope of mercury, having formula 
Number of protons in this isotope = 80
Number of neutrons in this isotope = 114
This isotope is radioactive in nature and under decay process by Electron Capture.
Electron capture reactions are the reactions in which a proton in a nucleus absorbs an electron and convert it into neutron. The resulting nucleus will have a decreased atomic number and same atomic mass.
Reaction for electron capture of mercury-194 follows:
They are of the same period and are similar in some form
Answer:
The mass of board is 1.52 g.
Explanation:
Given data:
Density of wood = 0.487 g/cm³
Length of board = 3.21 cm
Width of board = 12.2 cm
Height of board = 0.80 mm (0.80/10=0.08 cm)
Mass of board = ?
Solution:
We know that density of an object is equal to the mass of substance divided by its volume. So we can calculate the mass from density formula.
Formula:
D = m/v
d = density
m = mass
v = volume
Now we will calculate the volume first.
V = length × width × height
V = 3.21 cm × 12.2 cm × 0.08 cm
V = 3.13cm³
Now we will calculate the mass.
D = m/v
0.487 g/cm³ = m/ 3.13 cm³
m = 0.487 g/cm³ × 3.13 cm³
m = 1.52 g
The mass of board is 1.52 g.
