Discuss two disadvantages of biotechnology and calculate the percentage composition by mass of oxygen in Ca(NO3)2.

Biotechnology raises significant ethical concerns, particularly regarding genetic engineering and cloning. Issues such as the manipulation of human genes, the creation of genetically modified organisms (GMOs), and the potential for unintended consequences on biodiversity and ecosystems are often debated.

There are concerns about potential health risks associated with consuming genetically modified foods, such as allergic reactions or the transfer of antibiotic resistance. Environmentally, the release of GMOs could lead to the development of herbicide-resistant weeds or pests, and the loss of genetic diversity in natural populations.

Here's the solution for question 4:

4) To calculate the percentage composition by mass of oxygen in $\text{Ca}(\text{NO}_3)_2$:

Given atomic masses: $\text{Ca} = 40$, $\text{N} = 14$, $\text{O} = 16$.
The formula $\text{Ca}(\text{NO}_3)_2$ means there is 1 Calcium atom, 2 Nitrogen atoms (since $\text{N}$ is inside the parenthesis and multiplied by 2), and 6 Oxygen atoms ($3 \times 2 = 6$).

There are 6 oxygen atoms in the compound.

The percentage composition by mass of oxygen in $\text{Ca}(\text{NO}_3)_2$ is $\boxed{\text{58.54\%}}$.