Each statement in the key is called

In any $\triangle ABC$,the expression $\frac{(a+b+c)(b+c-a)(c+a-b)(a+b-c)}{4b^2c^2}$ is equal to:

In gel electrophoresis,the separated bands of $DNA$ are cut out and extracted from the gel piece. This step is called

$2, 3$-dimethylhexane contains tertiary,secondary,and primary carbon atoms,respectively:

The molar mass of a solute $X$ in $g \ mol^{-1}$,if its $1 \%$ solution is isotonic with a $5 \%$ solution of cane sugar (molar mass $= 342 \ g \ mol^{-1}$),is

Which of the following is an unsuitable habitat for algae?