A stable isotope has just<em> the right number of neutrons for the number of protons </em>(the <em>n:p ratio</em>) to hold the nucleus together against the repulsions of the protons.
A radioactive isotope has either too few or too many neutrons for the nucleus to be stable,
The nucleus will then emit <em>alpha, beta, or gamma radiation</em> in an attempt to become more stable.
Answer:
The reaction begins and builds up heat. This heat causes the aluminum to melt and float on top of the liquid bromine. Wherever the two elements meet, sparks, heat, and light are given off.
Explanation:
Answer: D. 19.9 g hydrogen remains.
Explanation:
To calculate the moles, we use the equation:
a) moles of 
b) moles of 
According to stoichiometry :
1 mole of require 1 mole of
Thus 0.0787 moles of 
require=
of
Thus is the limiting reagent as it limits the formation of product and acts as the excess reagent. (10.0-0.0787)= 9.92 moles of are left unreacted.
Mass of 
Thus 19.9 g of remains unreacted.
- By changing three atom bond angle , we can change molecular polarity. if bond angle is 120° and all atom has same electronegativity, the resultant polarity ( dipole moment ) become zero. we can change bond anngle either less than or greater than 120°, but not exactly 120
- Replacing one or more atom with different atoms having electro negativity values also make molecular poles.
- By placing molecules under external electric field or magnetic field also causes to the molecule.
