GK (Science)

Calcium oxide has the chemical formula CaO. Calcium has a +2 charge and oxygen has a -2 charge, so they combine in a 1:1 ratio to form a neutral compound.

Hydrogen (H) is the most abundant element in the universe, making up about 75% of all normal matter by mass. Helium (He) is second most abundant. Silicon (Si) is common on Earth but not in the universe.

In a neutral atom, the number of electrons equals the number of protons. This balance of positive and negative charges gives the atom its overall neutral charge. If there are 11 protons, there must be 11 electrons for neutrality.

Poliovirus attacks the nervous system, specifically the motor neurons in the spinal cord that control muscle movement. This leads to paralysis, most commonly in the legs. The virus does not directly target lungs, brain, or kidneys as its primary effect.

NaCl is the chemical formula for sodium chloride, commonly known as table salt. It consists of one sodium atom (Na) bonded to one chlorine atom (Cl). Sodium chlorine is not the correct name, and soda ash refers to sodium carbonate (Na2CO3).

The atomic nucleus contains protons (positively charged) and neutrons (neutral). Electrons orbit outside the nucleus. The number of protons determines the element's identity, while neutrons contribute to nuclear stability and create isotopes.

Opposite magnetic poles attract each other. A north magnetic pole is attracted to a south magnetic pole. Like poles repel - north repels north, and south repels south. This fundamental principle explains how magnets interact.

Lead is a key component in lead-acid storage batteries, used in cars and backup power systems. Lead plates and sulfuric acid create the electrochemical reaction. Lead is too heavy and toxic for use in fans, TVs, or bicycles.

Copper is an excellent electrical conductor due to its low resistivity and availability. This is why it's the standard material for electrical wiring. Wood is an insulator, and while iron conducts electricity, copper has significantly better conductivity (about 6 times better than iron).

Helium's chemical symbol is He, not H2. H2 represents hydrogen gas (two hydrogen atoms bonded together). The question asks for the WRONG combination, and Helium-H2 is indeed incorrect because H2 belongs to hydrogen, not helium.

Plasma is considered the fourth state of matter, after solid, liquid, and gas. It consists of ionized gas with free electrons and ions, found in stars, lightning, and neon signs. Plasma is unique in responding to electromagnetic fields.

The ozone layer absorbs harmful ultraviolet (UV) radiation from the sun, protecting living organisms on Earth. It does not protect against meteorites or infrared light. UV radiation can cause skin cancer and damage ecosystems.

Georges Claude (G. Claude) invented the neon lamp in 1910. He discovered that passing an electric current through neon gas in a sealed tube produced a bright red glow. George Mendel is not associated with this invention.

Fish use gills to extract oxygen from water during respiration. Lungs are used by mammals and other terrestrial animals for breathing air, not by fish. Ears are for hearing, not respiration.

Diamond is the hardest naturally occurring substance known, ranking 10 on the Mohs scale of mineral hardness. The softest elements would be materials like talc, while 'mixed element' is not a standard classification.

Thomas Edison invented the first commercially practical incandescent light bulb in 1879. While other scientists like Swan had earlier versions, Edison's was the first successful and widely adopted design. Newton worked on gravity, Galileo on astronomy, and Marconi on radio.

An electric bulb converts electrical energy into light energy (and some heat energy). This is the fundamental principle of how incandescent and LED bulbs work - they transform electricity into visible light. Sound energy production would be a speaker, while mechanical energy conversion relates to motors and generators.

Seismology is the scientific study of earthquakes and the propagation of elastic waves through the earth. Botany studies plants, zoology studies animals, and petrology/geology studies rocks. Seismologists use seismographs to measure and record earthquake vibrations.

During daylight, plants perform photosynthesis, taking in carbon dioxide (CO2) and releasing oxygen (O2) as a byproduct. At night, they primarily respire, taking in O2 and releasing CO2. Options B and C incorrectly state the gas exchanges, and D is wrong because photosynthesis does occur during the day.

A microscope is specifically designed to magnify very small objects that cannot be seen with the naked eye. Telescopes are for viewing distant objects in space, binoculars for distant terrestrial objects, and spectacles are vision correction lenses, not magnification tools.

Pascal (Pa) is the SI unit of pressure, defined as one newton per square meter. Force is measured in newtons, work in joules, and light intensity in lumens or candelas. The pascal is commonly used to measure tire pressure, blood pressure, and atmospheric pressure variations.