Elements And Metals Quiz 1 - General Science - Current Affairs MCQ

Brass discolours in air primarily due to the presence of hydrogen sulphide (H₂S). Here's why:

- Composition of Brass: Brass is an alloy of copper and zinc. The copper in brass reacts with hydrogen sulphide.
- Reaction: When exposed to air containing hydrogen sulphide, copper forms a dark tarnish called copper sulfide.
- Result: This tarnishing effect causes the brass to appear discoloured.

Thus, option B, hydrogen sulphide, is the correct answer.

The only nonmetal that is a liquid at room temperature is bromine. Of course, mercury is also a liquid at room temperature, but is a metal.

Almost all metals can form amalgams with mercury, the notable exceptions being iron, platinum, tungsten, and tantalum. Silver-mercury amalgams are important in dentistry, and gold-mercury amalgam is used in the extraction of gold from ore.

The core of a pencil does not contain lead and never has. Pencils contain a form of solid carbon known as graphite. The Pencil by Henry Petroski, the graphite pencil was first developed and popularized in the 1600's. The first users of graphite simply dug this mineral out of the hills and discovered it could be sawed into sticks and used as an excellent writing tool. During the 1600's, no one knew the chemical nature of this material, as chemistry itself was still in its infancy. Since this writing material behaved similar to metallic lead, but had a darker color, people began calling it "black lead". Eventually, the name of the core of the pencil got shortened to "lead". In 1779, German chemist K. W. Scheele finally determined pencil lead to be composed of pure carbon. A decade later, A. G. Werner decided that this carbon material needed a new name and proposed the name "graphite" based on the Greek word "graphein" which means "to write". Black-core pencils currently contain and have always contained graphite, not lead.

One such chelate is chlorophyll, the green pigment of plants. In chlorophyll the central ion is magnesium, and the large organic molecule is a porphyrin. The porphyrin contains four nitrogen atoms that form bonds to magnesium in a square planar arrangement.

Water is a simple compound with a set of unique properties that are essential for life.

The chemical formula for water is H2O and its proper chemical name is dihydrogen monoxide. Water contains two parts hydrogen to one part oxygen. The ratio of these elements determines the molecular formula.

There is no vacuum in the electric bulb. On the contrary, argon gas or argon gas mixed with a little nitrogen is filled in the bulb under some pressure. Years ago there was a practice to leave vacuum inside the bulb so as to prevent the burning of tungsten filament in the temperature of 2000deg Celsius inside the bulb.

What is the scientific name for washing soda?

Sodium carbonate (also known as washing soda or soda ash), Na₂CO₃ is a sodium salt of carbonic acid.

Scientific name for baking soda?

Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula NaHCO₃. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. Since it has long been known and is widely used, the salt has many related names such as baking soda, bread soda, cooking soda, and bicarbonate of soda.

The only stable form under normal conditions is alpha quartz, in which crystalline silicon dioxide is usually encountered. In nature, impurities in crystalline α-quartz can give rise to colors. The high-temperature minerals, cristobalite and tridymite, have both lower densities and indices of refraction than quartz. Since the composition is identical, the reason for the discrepancies must be in the increased spacing in the high-temperature minerals. As is common with many substances, the higher the temperature, the farther apart the atoms are, due to the increased vibration energy.

In order, the most abundant greenhouse gases in Earth's atmosphere are:
* water vapor
* carbon dioxide
* methane
* nitrous oxide
* ozone
* chlorofluorocarbons

Bromine is a chemical element with symbol Br and atomic number 35. It is the third-lightest halogen, and is a fuming red-brown liquid at room temperature that evaporates readily to form a similarly coloured gas. Its properties are thus intermediate between those of chlorine and iodine.

Diamond is the hardest naturally occurring substance found on Earth. But it is not the hardest substance. Wurtzite boron nitride (synthetic) and lonsdaleite (which comes from meteorites) are both harder.

Peat is formed from the Bryophyta known as Sphagnum which is an aquatic bryophyta and since bryophytes are the earlier known land plants and they form a soft black or brown depositions in damp areas where they grows and with the age they got decayed and form peat hence the Sphagnum is also known as "Peat Moss"

A gasoline-fueled reciprocating engine requires fuel of sufficient octane rating to prevent uncontrolled combustion known as engine knocking (knock or ping). Antiknock agents allow the use of higher compression ratios for greater efficiency and peak power.

Graphite is used as a lubricant due to its slippery nature. Graphite has layers of carbon atoms, with weak forces, residing in between its layers because of which it is quite slippery.. 

Due to its loosely intact carbon atoms or free electrons, they can move around easily from one place to another, making graphite a good conductor of electricity.

Helium is an inert gas that is less narcotic than nitrogen at equivalent pressure (in fact there is no evidence for any narcosis from helium at all), so it is more suitable for deeper dives than nitrogen. Helium is equally able to cause decompression sickness. At high pressures, helium also causes high-pressure nervous syndrome, which is a central nervous system irritation syndrome which is in some ways opposite to narcosis.

Because oxygen react with acetylene and form oxyacetylene gas which helps in welding process.

Deliquescence is the process by which a substance absorbs moisture from the atmosphere until it dissolves in the absorbed water and forms a solution.Deliquescence occurs when the vapour pressure of the solution that is formed is less than the partial pressure of water vapour in the air.

Diamond is the naturally occurring substance it is found rarely and costly but silicon carbide is man mad substance so mostly try to use the silicon carbide is used for cutting very hard substances.

The average salinity of water is approximately 3.5%, or 35 parts per thousand. 

This implies that for every 1 litre of sea water there are 35 grams of salts dissolved in it. 

Even though a vast majority of seawater is found in oceans with salinity around 3.5%, seawater is not consistently saline throughout the world.