Carbon-14 has a half-life of 5720 years and this is a first-order reaction. If a piece of wood has converted 11.5% of the carbon-14, then how old is it? 4290 years 2375 years 17160 years 4750 years 1008 years

1008 years

Explanation:

Given that:

Half life = 5720 years

Where, k is rate constant

So,  

The rate constant, k = 0.00012 year⁻¹

Using integrated rate law for first order kinetics as:

Where,  

is the concentration at time t

is the initial concentration

Given:

11.5 % is decomposed which means that 0.115 of is decomposed. So,

= 1 - 0.115 = 0.885

t = ?

t = 1008 years

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

→

they are made of gases.

they have a spherical shape.

they make energy through fusion.