Identify the element x in the following nuclear reactions: (a) h+be → x + n; (hint: see appendix e.)

Boron

Explanation:

(a)

H means hydrogen

The atomic mass of hydrogen is 1 and the mass number is 2.

Be means beryllium

The atomic number is 4 and the mass number is 9.

n mean neutron, atomic number is 0 and mass number 1.

By conserving the charge,

the atomic number of X = 1 + 4 - 0 = 5

the mass of X = 2 + 9 - 1 = 10

The element having atomic number 5 and mass number 10 is Boron (B).

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =