The correct answer should be B.
The correct answer would be B.
Answer:
3 × 10^8 m/s
Explanation:
The wavelength, can be calculated by using the following formula;
λ = v/f
Where;
λ = wavelength (m)
v = velocity/speed of light (m/s)
f = frequency (Hz)
According to the provided information in this question, λ = 600nm i.e. 600 × 10^-9m, f = 5.00 x 10^14 Hz
Hence, using λ = v/f
v = λ × f
v = 600 × 10^-9 × 5.00 x 10^14
v = 6 × 10^-7 × 5.00 x 10^14
v = 30 × 10^(-7 + 14)
v = 30 × 10^ (7)
v = 3 × 10^8 m/s
Given, half life of a certain radioactive element = 800 years.
Amount of substance remaining at time t = 12.5%
Lets consider the initial amount of the radioactive substance = 100%
Using the half life equation:
A = A₀(1/2)^t/t₁/₂
where A₀ is the amount of radioactive substance at time zero and A is the amount of radioactive substance at time t, and t₁/₂ is the half-life of the radioactive substance.
Plugging the given data into the half life equation we have,
12.5 = 100 . (1/2)^t/800
12.5/100 = (1/2)^t/800
0.125 = (0.5)^t/800
(0.5)^3 = (0.5)^t/800
3 = t/800
t = 2400 years
Thus the object is 2400 years old.
The periodic table of elements is divided into columns and rows. The vertical columns represent the groups while the horizontal rows represent the periods. A group of elements usually have similar physical and chemical properties. The first column of the periodic table is made up of 7 elements including SODIUM.
1. The name of the element chosen is sodium and its chemical symbol is Na.
2. Sodium is a metal and thus it has metallic properties.
3. Sodium belongs to group one elements whose family name is ALKALI METALS.
4. The neutral atom of sodium is made up of 11 protons, 11 electrons and 12 neutrons.
