Questions

A 40% solution of Formaldehyde known as Formalin is used in the preservation of biological specimens because of its hardening action on proteins. 

Capital refers to buildings and equipment i.e, goods which are used by workers to produce other goods such as machinery, land, ...

Capital has a number of related meanings in economics, finance, and accounting.

In economics, Capital comprises one of the four major factors of production, the others being land, labor, and entrepreneurship.

In finance and accounting, capital generally refers to financial wealth, especially that used to start or maintain a business.

Biodegradable substances can be broken down into simpler, harmless substances in nature with due course of time by the biological process such as action of microbes. They can be recycled as a part of food chain.

Here, Leather bags are biodegradable.

A greenhouse gas is a gas in an atmosphere that absorbs and emits radiant energy within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. 

Carbon dioxide is a main greenhouse gas, found in car exhaust pipes.
Methane and nitrous oxide is another type of greenhouse gas.

Oxygen is the only clean gas out there because we need it to survive. Therefore, the only gas that is not a greenhouse gas is Oxygen.

Crossover rates have to do with the amount of earnings that are generated by two different but similar projects. The crossover rate is the point at which the two projects achieve the same net present value. In terms of investments, calculating a crossover rate between two similar securities can help an investor determine what to buy and what to sell.