Answer: A) Economic resources are limited. Explanation: Economic resources are those goods and services that can be converted into valuable products for individual and business purposes. There are four major types of economic resources: 1. land, 2. labor, 3. capital and 4. entrepreneurship.   Land and labor are natural and human resources, while capital means physical resources or money. Entrepreneurship converts these resources into usable goods.   However, resources have finite values, and proper utilization depends on economic systems and economic decisions.

Answer: A) TRUE Explanation: Milk is converted into curd or yogurt by the process of fermentation. Milk consists of globular proteins called casein.    It is biochemical change because here microorganism named lactobacillus react with milk and turn it to curd. Lactobacillus required favourable condition to grow. For it 37 degree temperature is needed. But sometimes when it does not get favourable condition, then other microorganism react and makes the curd taste different.

Answer: A) Acid rain Explanation: Secondary pollutants include ozone, which is formed when hydrocarbons (HC) and nitrogen oxides (NOx) combine in the presence of sunlight.   Whereas Primary pollutant are those pollutants that are directly emitted from their sources, like CO2, CO, SO2 as these gases are directly emitted form burning of fossil fuels.   Acid rain, which is formed when sulfur dioxide or nitrogen oxides react with water, sulfuric acid etc.   Hence, Acidrain is a secondary air pollutant.

Answer: A) 330/29 m/s Explanation: Second gun shot take 30 sec to reach rahul imples distance between two. given speed of sound = 330 m/s Now, distance = 330 m/s x 30 sec    Hence, speed of the bus = d/t = 330x30/(14x60 + 30) = 330/29 m/s.

Any person can have only 1 birthday i.e, the day he was born. And every year we celebrate it's anniversaries.

Answer: B) FALSE Explanation: Mushrooms are heterotrophs. They are not plants or autotrophs.   Every living thing that exists need energy in order to live. This energy ultimately comes from the sun, and only plants, or autotrophs, can directly use this energy to make food. Those organisms that cannot harness the sun's energy are known as heterotrophs.   Mushrooms belong to kingdom Fungi and are heterotrophs because they decompose and consume nutrients from the soil. They are not green so they cannot photosynthesize For this reason, mushrooms and all other fungi are heterotrophs.

Answer: D) The sequence of amino acids in the polypeptide chain differs from protein to protein Explanation:

Answer: D) the capacity of layers of metal ions to slide over the other Explanation: