Elements, Compounds and Mixtures Test - 5

An atom is the smallest particle of anyelement that still retains the characteristics of that element. A piece of anelement that we are able to see or handle is made of many, many atoms and allatoms are the same. They all have the same number of protons.

Therefore, option(a) is correct.

Stainless steelis a metal alloy, made up of steel mixed with elements such as chromium,nickel, molybdenum, silicon, aluminum, and carbon. Iron mixed with carbonto produce steel is the main component of stainless steel. Chromium is added tomake it resistant to rust.

Therefore, option (a) is correct.

Elements, whichare composed of a single type of atom, contain different numbers of protons.Molecules are formed when two or more atoms bond together. If molecules containatoms of different elements, that substance is known as a compound.

Therefore, option (a) is correct.

An element is a pure substance that cannotbe broken down into simpler substances by chemical or physical means. Eachelement has unique physical and chemical properties.

Therefore, option (a) is correct.

Calcium is achemical element with the symbol Ca and atomic number 20. As an alkaline earthmetal, calcium is a reactive metal that forms a dark oxide-nitride layer whenexposed to air.  It is the fifth most abundant element in Earth's crust andthe third most abundant metal, after iron and aluminium.

Therefore, option (a) is correct. 

Igneous rocks areformed from lava or magma. Magma is molten rock that is underground and lava ismolten rock that erupts out on the surface. The two main types of igneous rocksare plutonic rocks and volcanic rocks. Plutonic rocks are formed when magmacools and solidifies underground.

Therefore, option (b) is correct. 

In total, 118 elements have been identified.The first 94 occur naturally on Earth, and the remaining 24 are syntheticelements. There are 80 elements that have at least one stable isotope and 38that have exclusively radionuclides, which decay over time into other elements.

Therefore, option(b) is correct.

H2O a.k.a wateris a COMPOUND because water has 2 different molecules which are chemicallybonded. H₂O can't be a mixture because it's bonded chemically and can't beseparated into H₂ and O by physical means. It can't be an element because H₂Oa.k.a water is made of atoms of different types (Hydrogen & Oxygen).

Chemistsordinarily work with weighable quantities of elements and compounds. Forexample, in the iron-sulfur equation the symbol Fe represents 55.845 grams ofiron, S represents 32.066 grams of sulfur, and FeS represents 87.911 grams ofiron sulfide.

Therefore, option c is correct.

Sediment inrivers gets deposited as the river slows down. Larger, heavier particles likepebbles and sand are deposited first, whilst the lighter silt and clay onlysettle if the water is almost still.

Therefore, option (a) is correct.

Hydrogen is seen as an element because, it is the simple and ample element in the world.

The reason for considering HYDROGEN as a chemical element because it is the lightest element and it is colorless, tasteless, and odorless.

Iron is described as an element because it is a pure substance. A pure substance is where the atoms are similar and cannot be divided into smaller.

Therefore, option (b) is correct.

When two or more elements chemically combine in a fixed ratio by mass, the obtained product is known as a compound. Compounds can be defined as substances consisting of 2 or more different types of elements in a fixed ratio of its atoms. When the elements combine, some individual property of the elements is lost and the newly formed compound has new properties.

Therefore, option (c) is correct.

During chemicalreactions, the bonds that hold molecules together break apart and form newbonds, rearranging atoms into different substances. Each bond requires adistinct amount of energy to either break or form; without this energy, thereaction cannot take place, and the reactants remain as they were.

Therefore, option(a) is correct. 

Sedimentary rocksare formed from overburden pressure as particles of sediment are deposited outof air, ice, or water flows carrying the particles in suspension.

Therefore, option (a) is correct.

Metamorphic rocksstart off as igneous, sedimentary, or other metamorphic rocks. These rocks arechanged when heat or pressure alters the existing rock's physical or chemicalmake up. One way rocks may change during metamorphism is by rearrangement oftheir mineral crystals.

Therefore, option(a) is correct. 

Rocks arecomposed of grains of minerals, which are homogeneous solids formed from achemical compound arranged in an orderly manner. The aggregate minerals formingthe rock are held together by chemical bonds. The types and abundance ofminerals in a rock are determined by the manner in which it was formed.

Therefore, option(a) is correct.