1. The method that cannot be used for removing permanent hardness of water is
- Adding sodium carbonate
- Adding caustic soda
Ans :- Option
Description :- Permanent hardness of water is caused by very soluble magnesium and slightly soluble calcium sulfate therefore it cannot be removed by boiling process.
2. Which of the following waves is used for communication by artificial satellite?
- The frequency of 101 series
- Radio waves
Description :- Microwaves are used to communicate with the geostationary satellites rather than the satellites that are orbiting in the low orbit. Radio waves are used to communicate with the satellites that are revolving in the lower orbit.
3. Cement is made hard by
- Hydration and dissociation of water
- Dissociation of water
Description:- Cement is made hard with hydration and dissociation of water. Cement starts to set when mixed with water, which causes a series of hydration chemical reactions. The constituents slowly hydrate and the mineral hydrates solidify. The interlocking of the hydrates gives cement its strength
4. Which one of the following metals pollutes the air of a city having large number of automobiles?
Description:- Lead is used in petrol. That’s why big cities are polluting by air pollution. Lead is lavish in polluting the ambient area of cities because it has heaviest particulate to react time and again quickly.
5. The ratio of pure gold in 18 carat gold is?
Description:- 18–karat gold is 18 parts gold, 6 parts another metal (forming an alloy with 75% gold)
6. The color of the eye depends ups the pigment present inside?
Description:- The color of your eyes depends on how much of the pigment melanin you have in your iris—the colored part of your eyes. The more pigment you have, the darker your eyes will be. Blue, grey, and green eyes are lighter because they have less melanin in the iris.
7. The number of chromosomes present in a normal human being is?
Description:- In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. Twenty-two of these pairs, called automates, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females
8. The disease that is caused by virus is?
- Common Cold
Description:- Viruses cause familiar infectious diseases such as the common cold, flu and warts. They also cause severe illnesses such as HIV/AIDS, smallpox, and Ebola. Viruses are like hijackers. They invade living, normal cells and use those cells to multiply and produce other viruses like themselves.
9. In which of the following substances all carbon atoms are quaternary in nature?