Exam Questions and CORRECT Answers
double-displacement reaction - CORRECT ANSWER - A double displacement reaction,
also known as a double replacement reaction or metathesis, is a type of chemical reaction where
two compounds react, and the positive ions (cation) and the negative ions (anion) of the two
reactants switch places, forming two new compounds or products
Precipitate - CORRECT ANSWER - precipitate is an insoluble solid that emerges from a
liquid solution. The emergence of the insoluble solid from solution is called precipitation. Often
the precipitate emerges as a suspension. Precipitates can form when two soluble salts react in
solution to form one or more insoluble products.
Energy Levels - CORRECT ANSWER - Energy levels (also called electron shells) are
fixed distances from the nucleus of an atom where electrons may be found. As you go farther
from the nucleus, electrons at higher energy levels have more energy. Electrons in the outermost
energy level of an atom are called valence electrons
Marquis Test - CORRECT ANSWER - The Marquis Test is commonly used for Ecstasy
testing as MDMA turns the precipitate purple black. Cobalt thiocyanate is used to test for
cocaine. The Cobalt is mixed with the questionable substance, then drowned in hydrochloric
acid, doused in chloroform, and shaken.
What is the relation between an atomic number and a mass number? - CORRECT
ANSWER - Atomic number is actually the number of protons in an atom while mass
number is the number of nucleons i. e, number of protons plus the number of neutrons.
Isotopes - CORRECT ANSWER - Isotopes refer to the nuclides of a certain element that
have different numbers of neutrons, or in other words, atomic nuclei that have the same number
of protons but different numbers of neutrons. A radioisotope is an isotope that is unstable and
therefore undergoes radioactive decay or will at some point.
Chemical Synthesis - CORRECT ANSWER - Chemical synthesis, the construction of
complex chemical compounds from simpler ones. It is the process by which many substances
, important to daily life are obtained. It is applied to all types of chemical compounds, but most
syntheses are of organic molecules.
Decomposition - CORRECT ANSWER - A decomposition reaction is a type of chemical
reaction in which a single compound breaks down into two or more elements or new compounds.
These reactions often involve an energy source such as heat, light, or electricity that breaks apart
the bonds of compounds
single-displacement reaction - CORRECT ANSWER - A single-displacement reaction,
also known as a single-replacement reaction, is a type of chemical reaction where an element
reacts with a compound and takes the place of another element in that compound. This type of
reaction is typically pictured like this: Here, A replaces B in the compound BC
Flame test - CORRECT ANSWER - flame test is an analytical procedure used in
chemistry to detect the presence of certain elements, primarily metal ions, based on each
element's characteristic emission spectrum. The color of flames in general also depends on
temperature; see flame color.
Precipitation reaction - CORRECT ANSWER - A precipitation reaction refers to the
formation of an insoluble salt when two solutions containing soluble salts are combined. The
insoluble salt that falls out of solution is known as the precipitate, hence the reaction's name.
Precipitation reactions can help determine the presence of various ions in solution.
organic compounds - CORRECT ANSWER - An organic compound is a substance that is
added to a product, like food, to improve some qualities such as taste, smell, colour and texture.
These substances can be both positive and negative for human health.
Synthetic materials - CORRECT ANSWER - Synthetic materials which are by-products of
petroleum are non-biodegradable, synthetic products take a long time to decompose, creating
long-term pollution. Nylon is hard to recycle, making them hard to decompose, accumulate
landfills more. Polyesters are easy to recycle, which makes them less harmful to the society.
Electronegativity - CORRECT ANSWER - Electronegativity is a measure of the tendency
of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used.