Questions

About 150 - 200 species of plant, insect, bird and mammal become extinct every day or 24 hrs.

This is not an accurate but an estimation by U.N. Convention on Biological Diversity and Global Extinction Rates. It is also said that current extinctions were 'up to 100 times higher than the background rate.'

Johann Strauss's on the Banks of the Beautiful Blue Danube

Brazil is one example of a closed economy in the given options. 

A closed economy is one that has no trade activity with outside economies. A closed economy is self-sufficient, which means no imports come into the country and no exports leave the country. A closed economy's intent is to provide domestic consumers with everything they need from within the country's borders.

The principle of dominance states that some alleles are dominant, while others are recessive.

Strength of concrete increases with increase in water cement ratio as the strength of the cement is directly proportional to water cement ratio.

According to Rayleigh's law, the intensity of scattered light varies inversely as the fourth power of its wavelength. Sunlight consists of seven colours. Of these, red has the maximum wavelength. During sunrise and sunset, the rays have to travel a larger part of the atmosphere because they are very close to the horizon.Therefore, light other than red is mostly scattered away. Most of the red light, which is the least scattered, enters our eyes. Hence, the sun and the sky appear red.