General Science: Chemistry and Biology Fundamentals

Angular cheilitis (cracking at mouth corners) is a classic sign of riboflavin (Vitamin B2) deficiency. This B vitamin is essential for skin and mucous membrane health. Other B vitamin deficiencies cause different symptoms: B1 (beriberi), B3 (pellagra), and B12 (anemia).

Distilled water is pure H2O and lacks the dissolved ions (electrolytes) necessary to conduct electricity. Acids like HCl and H2SO4 dissociate into ions, making them good conductors.

Mercury is a chemical element with the symbol Hg and is the only metallic element that is liquid at standard temperature and pressure.

Sodium hydroxide (caustic soda) is a versatile chemical used in the production of soaps, paper, synthetic fibers like rayon, and many other industrial products.

Gold is the most ductile metal, capable of being drawn into extremely thin wires without breaking. This property is due to its metallic bonding structure.

Mercury is a transition metal. Carbon is a non-metal, and silicon is a metalloid.

 The high solubility of bromide ions has caused its accumulation in the oceans.

Sodium and potassium are alkali metals that are soft enough to be cut with a knife. Since both are correct, option C is the appropriate choice.

Malaria is a vector-borne disease transmitted to humans through the bite of an infected female Anopheles mosquito. Male mosquitoes feed on plant nectar and do not bite humans.

Hazard warning signs are used to alert individuals to the presence of dangerous substances, including corrosive acids and bases. These symbols help prevent accidental exposure or injury.

Diamond is an allotrope of carbon and is known as the hardest naturally occurring substance. While most non-metals are brittle or soft, diamond's unique crystal structure gives it extreme hardness.

The liver is the primary site for the urea cycle, where ammonia, a toxic byproduct of protein metabolism, is converted into urea. Urea is then transported to the kidneys for excretion.

Most non-metals are dull, but iodine is a notable exception that exhibits a metallic luster. It appears as a dark, shiny, crystalline solid at room temperature.

Quinine is a natural white crystalline alkaloid that has antipyretic, antimalarial, and analgesic properties. It is traditionally extracted from the bark of the Cinchona tree.

Both Gallium and Cesium have very low melting points. Gallium melts at approximately 29.76 degrees Celsius, and Cesium melts at approximately 28.44 degrees Celsius, making both capable of melting in or near human hand temperatures.

Strong mineral acids like HCl, HNO3, and H2SO4 are highly corrosive and react with most metals. Therefore, they are typically stored in glass or specialized plastic containers rather than metal ones.

The taste of a base is bitter.

Iron filings have a much larger surface area compared to a solid block of iron metal. This increased surface area allows them to react more readily with oxygen in the air, causing them to burn easily.

Aqueous solutions conduct electricity if they contain ions. Hydrochloric acid (HCl) dissociates into H+ and Cl- ions in water, allowing it to conduct electricity, whereas glucose and ethyl alcohol are covalent compounds that do not ionize.

On the pH scale, which ranges from 0 to 14, a value of 7 is considered neutral. Values less than 7 are acidic, and values greater than 7 are basic.

Aqua regia is a highly corrosive mixture of concentrated nitric acid and concentrated hydrochloric acid, typically prepared in a molar ratio of 1:3.

Rusting is the chemical process where iron reacts with oxygen and moisture to form hydrated iron(III) oxide. This process is a common example of metal corrosion.

An acidic solution has a higher concentration of hydrogen ions, which corresponds to a pH value of less than 7 on the pH scale.

The pH scale is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. It is the standard tool for measuring the strength of acids and bases.

Nitrogen makes up about 78 percent of the Earth's atmosphere and is relatively inert. Its presence dilutes oxygen, which prevents combustion from occurring too rapidly or uncontrollably.