Day 17: Static Quiz on Science

Correct Answer : C Justification, In china, some of the commonly exploited minerals and compounds include magnesium, potassium
nitrate, boron salt, lithium salts, Rubidium and Caesium, uranium and thorium.

Correct Answer: C Justification :
Statement 1: Since ammonia occurs naturally in the environment, we are regularly exposed to low levels of ammonia in air, soil, and water. Ammonia exists naturally in the air at levels between 1 and 5 parts in a billion parts of air (ppb). It is commonly found in rainwater.
Ammonia is naturally produced and used by all mammals in their normal metabolism. Ammonia is produced within a person’s body each day.
Statement 2: Ammonia does not last very long in the environment. Because it is recycled naturally, nature has many ways of incorporating and transforming ammonia. In soil or water, plants and microorganisms rapidly take up ammonia. After fertilizer containing ammonia is applied to the soil, the amount of ammonia in that soil decreases to low levels in a few days.
Statement 3: Both gaseous and particulate ammonia contribute to eutrophication of surface waters, soil acidification, fertilization of vegetation, changes in ecosystems and smog and decreased visibility in cities and pristine areas.

Correct Answer : C
Answer Justification :
Justification: A microwave oven heats food by passing microwave radiation through it. Microwaves are a form of non-ionizing electromagnetic radiation with a frequency higher than ordinary radio waves but lower than infrared light. Microwave ovens use frequencies in one of the ISM (industrial, scientific, medical) bands, which are reserved for this use, so they do not interfere with other vital radio services.
It induces polar molecules in the food to rotate and produce thermal energy. Since water is a polar molecule, the most appropriate option here is (c).
They are also useful for rapid heating of otherwise slowly prepared cooking items, such as hot butter, fats, and chocolate. Unlike conventional ovens, microwave ovens usually do not directly brown or caramelize food, since they rarely attain the necessary temperatures.

Correct Answer: C
Justification: Statement 1: As a halogen, chlorine is a highly efficient disinfectant, and is added to public water supplies to kill disease-causing pathogens, such as bacteria, viruses, and protozoans, that commonly grow in water supply reservoirs, on the walls of water mains and in storage tanks.
Statement 2: Disinfection by chlorination can be problematic, in some circumstances. Chlorine can react
with naturally occurring organic compounds found in the water supply to produce compounds known as disinfection by-products (DBPs). The most common DBPs are trihalomethanes (THMs) and haloacetic acids (HAAs).
Trihalomethanes are the main disinfectant by-products created from chlorination with two different types, bromoform and dibromochloromethane, which are mainly responsible for health hazards. Their effects depend strictly on the duration of their exposure to the chemicals and the amount ingested into the body. In high doses, bromoform mainly slows down regular brain activity, which is manifested
by symptoms such as sleepiness or sedation.

Correct Answer : D
Justification: Ions are atoms or molecules containing a total number of electrons that are not equal to the total number of protons.
There are two different groups of ions, cations, which are positively charged, and anions, which are negatively charged.
Ion exchange is an exchange of ions between two electrolytes or between an electrolyte solution and a complex. In most cases the term is used to denote the processes of purification, separation, and decontamination of aqueous and other ion-containing solutions with solid polymeric or mineralic “ion exchangers”.
Ion exchange is widely used in the food and beverage industry, hydrometallurgy, metals finishing, chemical, petrochemical and pharmaceutical technology, sugar and sweetener production, ground- and potable-water treatment, nuclear, softening and industrial water treatment, semiconductor, power, and a host of other industries.
A typical example of application is the preparation of high-purity water for power engineering, electronic and nuclear industries; i.e. polymeric or mineralic insoluble ion exchangers are widely used for water softening, water purification, water decontamination, etc

Correct Answer : C
Answer Justification :
Justification: As the only element or metal that is liquid at room temperature, it is used in many common
household products and fixtures.

It is contained in the following products: thermometers (looks like a silvery liquid); thermostats; blood- pressure cuffs; barometers; fluorescent and high-intensity discharge (HID) lamps; mercurochrome; auto switches; float switches; button-cell batteries; old latex paint; some oil-based paints; old alkaline batteries;
chemistry sets; old fungicides for seeds and turf; dental amalgam; some imported jewelry (glass ampoules with silver liquid); weight/counterweight in grandfather clocks.
Statement 2: Button cell batteries use Mercury, not Laptop batteries. Mercury can enter our bodies through our lungs and skin, or more commonly, by eating mercury-contaminated fish.

Correct Answer : B
Justification: Statement 1: Ice-VII, a form of ice, is formed in a diamond.
Diamonds often pick up molecules during their formation deep in the Earth. These so-called inclusions can affect the quality or color of the diamond, but sometimes the inclusion is just water.

One interesting property of diamonds is the internal structures don’t relax when they leave the high-pressure mantle.

So, the water inside a diamond remains compressed, even though it’s technically in a liquid state.
Statement 2: A Commonly used form of Ice is called as ice-I. When water freezes, the oxygen atoms move into a hexagonal arrangement. That’s why ice expands and has lower density than water. Compressing ice can change the shape of the crystals, turning ice-I into ice-
II (rhombus-shaped crystals), ice-III (tetragonal crystals), and so on.

Statement 3: The formation of ice-VII doesn’t require freezing temperatures — as long as the pressure is high enough, ice-VII can form at room temperature.

Correct Answer : A
Justification: Statement 3 and 4: The five elements niobium, molybdenum, tantalum, tungsten and rhenium are included in the definition of refractory metals. The wider definition of refractory metals includes all elements with a melting point above 2,123 K (1,850 °C), includes a varying number of nine additional elements: titanium, vanadium, chromium, zirconium, hafnium, ruthenium.

Statement 1 and 2: A fusible alloy is a metal alloy capable of being easily fused, i.e. easily meltable, at relatively low temperatures.
Low melting alloys can be divided up into: Mercury-containing alloys Only alkali metal-containing alloys Gallium-containing alloys (but neither alkali metal nor mercury)

Only bismuth, lead, tin, cadmium, zinc, indium and sometimes thallium-containing alloys

Correct Answer : B

Justification: Statement 1: It exhibits poor thermal conductivity but shows good electrical conductivity. The material having thermoelectric properties is made from silver, copper, and tellurium.

It shows high levels of thermoelectric performance i.e. exhibits poor thermal conductivity in 25-425 degree C range but shows good electrical conductivity.

Statement 2: Due to its low thermal conductivity, one end of 8 mm-long AgCuTe rod which is contact with waste heat remains hot while another end maintains cold temperature.

This temperature difference results in the generation of electrical voltage. The material also exhibits good electrical conductivity like metal at the same time.

Correct Answer: A

Learning: Indian scientists have developed a supercritical carbon dioxide Brayton test loop facility that would help generate clean energy from future power plants including solar thermal.

The efficiency of energy conversion could be significantly increased by as much as 50% or more if S-CO2 is operated in a closed loop Brayton cycle. Besides increasing power generation and making the

process more efficient, there are other advantages of using this new technology. Smaller turbines and power blocks can make the power plant cheaper, while higher efficiency would significantly reduce CO2 emissions for fossil fuel-based plants. Moreover, if the power plant used solar or nuclear heat source, it would mean higher capacity at lower operating costs.