Ancient Greek scholars believed all things were made of how many basic elements?
- a2
- b3
- c4
- d5
261 questions · 27 sections
Ancient Greek scholars believed all things were made of how many basic elements?
Which of the following was NOT considered a basic element by ancient Greeks?
Who first proposed that all substances have a very small, indivisible unit?
The word "Atom" was first introduced by:
Why did Democritus's idea of the atom not get recognition?
Which great scientist of ancient times opposed the idea of the atom?
The British scientist John Dalton proposed his atomic theory in:
After how many years of Democritus's idea did Dalton give his theory?
According to Dalton, every matter of the universe is made of:
Later, an atom was proved to be divisible into:
A pure substance that yields nothing but itself when divided is called a/an:
So far, how many elements have been discovered in total?
How many of the discovered elements are available in nature?
Elements made in the laboratory are called:
How many different elements are present in the human body?
Which of the following is NOT an example of an element?
Which of the following sets contains only elements?
Number of synthetic elements is:
When pure gold is broken down repeatedly, what is obtained?
Helium and argon are examples of which type of element?
The substance which yields two or more elements when divided is called:
Chemical analysis of water yields:
The ratio of hydrogen to oxygen atoms in water is:
In a compound, the elements are always present in:
Chemical analysis of writing chalk gives:
At room temperature, hydrogen and oxygen are gases, but their compound water is:
The properties of a compound are:
Which of the following is a compound?
If we collect water samples from any place, the ratio of H to O atoms will be:
The minimum number of elements required to form a compound is:
The smallest particle of an element that contains the characteristics of that element is called:
Two or more atoms connected by a chemical bond form a:
The molecule of oxygen is:
is formed when one carbon atom bonds with how many oxygen atoms?
When atoms of different elements bond together, the molecule is called:
is an example of:
is an example of:
Nitrogen atoms contain the characteristic features of:
Detailed concepts of chemical bonds are discussed in chapter:
Which of the following represents a molecule of carbon dioxide?
The symbol of an element is the abbreviated form of its:
The first letter of the symbol of an element is always written in:
The symbol of Hydrogen is:
The symbol of Carbon is:
The symbol of Oxygen is:
The symbol of Chlorine is:
The symbol of Calcium is:
The symbol of Cobalt is:
The symbol of Cadmium is:
The symbol of Chromium is:
The Latin name of Sodium is:
The Latin name of Copper is:
The Latin name of Potassium is:
The Latin name of Silver is:
The Latin name of Tin is:
The Latin name of Antimony is:
The Latin name of Gold is:
The Latin name of Lead is:
The Latin name of Tungsten is:
The Latin name of Iron is:
The Latin name of Mercury is:
The symbol Na denotes:
The symbol K denotes:
The symbol Ag denotes:
The symbol Au denotes:
The symbol Pb denotes:
The symbol Fe denotes:
The symbol Hg denotes:
The symbol W denotes:
Hydrogen molecule is expressed as:
The formula implies that one molecule of hydrogen contains:
The formula of water is:
The formula of nitrogen molecule is:
The formula of ammonia is:
The formula of chlorine molecule is:
The formula of sulfuric acid is:
The formula of hydrochloric acid is:
One molecule of water contains how many oxygen atoms?
One molecule of contains how many hydrogen atoms?
Each atom consists of how many types of stable fundamental particles?
Which particles reside at the centre or nucleus of the atom?
Electrons in an atom move:
Which is NOT a fundamental particle of the atom (per textbook)?
Protons and neutrons in the atom together are called:
The charge of an electron is:
The mass of an electron is:
The relative charge of an electron is:
The relative mass of an electron is taken as:
The mass of an electron is how many times less than the mass of a proton or neutron?
An electron is denoted by the symbol:
The charge of a proton is:
The mass of a proton is approximately:
The relative charge of a proton is:
The relative mass of a proton is:
A proton is denoted by:
Protons are located:
The charge of a neutron is:
The relative mass of a neutron is:
The actual mass of a neutron is:
Which atom does NOT contain a neutron?
The mass of a neutron is:
A neutron is symbolized by:
The atomic number of an element equals the number of:
Atomic number is denoted by:
The atomic number of Helium is:
The atomic number of Oxygen is:
The atomic number of Hydrogen is:
If atomic number = 9, the element is:
The "ID number" of an element refers to its:
Since atoms are charge-neutral, the number of electrons equals the number of:
The atomic number of Potassium is:
The mass number of an atom is the total number of:
Mass number is denoted by:
The mass number of Sodium is:
Sodium has 11 protons. The number of neutrons in is:
The mass number is written at the:
The atomic number is written at the:
For , the number of neutrons is:
For , the number of neutrons is:
For , the number of protons is:
Number of neutrons = mass number minus:
Rutherford proposed his atomic model in:
According to Rutherford, the central core of the atom is:
The dense central core of the atom is called the:
According to Rutherford, most of the space inside an atom is:
Rutherford's model is also known as the:
The motion of electrons around the nucleus, according to Rutherford, is compared to:
The force that keeps electrons moving around the nucleus is:
The overall charge of an atom according to Rutherford's model is:
Which of the following is a limitation of Rutherford's model?
According to Maxwell's electromagnetic theory, a charged particle moving in a circular path will:
According to Rutherford's parallel with the solar system, what is the issue?
Rutherford's model could not satisfactorily explain atoms containing:
Bohr's atomic model was given in:
The orbits in Bohr's model are also called:
According to Bohr, electrons in fixed orbits:
Bohr's quantization condition is:
In , stands for:
The value of Planck's constant is:
When , the principal energy level is named:
When , the principal energy level is:
When , the principal energy level is:
When , the principal energy level is:
An electron absorbs energy when it:
An electron emits energy when it:
The energy absorbed or emitted by an electron is:
In , represents:
The atomic spectrum is created when light passes through a:
Bohr's model successfully explains the atomic spectrum of:
A limitation of Bohr's model is that it cannot explain the spectrum of atoms with:
According to high-resolution apparatus, each line in the spectrum:
Bohr assumed orbits to be circular, but later they were proved to be:
The velocity of light used in Bohr's model is:
The maximum number of electrons in an energy level is given by:
The K-shell () can hold a maximum of:
The L-shell () can hold a maximum of:
The M-shell () can hold a maximum of:
The N-shell () can hold a maximum of:
Electronic configuration of Lithium () is:
Electronic configuration of Sodium () is:
Electronic configuration of Argon () is:
The 19th electron of Potassium enters which shell?
According to the Bohr 2n² rule alone, M shell should hold up to 18, but Potassium's 19th electron goes to:
Subshells of an energy level are denoted by the letter:
The values of for a given range from:
Sublevels are also called:
For , how many orbitals are there?
For , how many orbitals exist?
For , the orbitals are:
For , the orbitals are:
The maximum number of electrons in an s orbital is:
The maximum number of electrons in a p orbital is:
The maximum number of electrons in a d orbital is:
The maximum number of electrons in an f orbital is:
The number of subshells in a principal energy level is:
Total electrons in an orbital are given by:
Which is NOT one of the three principles of electronic configuration?
According to the Aufbau principle, an electron first enters the orbital with:
The energy of an orbital is determined by the value of:
For 3d orbital, the value of is:
For 4s orbital, the value of is:
Which orbital has lower energy: 3d or 4s?
If two orbitals have the same value, the one with lower energy has:
For 3d and 4p, both have . Which is lower in energy?
The correct sequence of orbital filling starts with:
After 4s, the next orbital filled is:
After 3d, the next orbital filled is:
The electronic configuration of () is:
The electronic configuration of () is:
The electronic configuration of () is:
The electronic configuration of () is:
The expected electronic configuration of () is , but the actual configuration is:
The actual electronic configuration of () is:
The exceptional behavior of Cr and Cu is due to extra stability of:
Half-filled d configuration is denoted by:
Fully-filled d configuration is denoted by:
To make 3d half-filled in Cr, an electron from shifts to:
Atoms of the same element with same number of protons but different numbers of neutrons are called:
Hydrogen has how many isotopes in total?
How many naturally occurring isotopes of hydrogen are there?
The hydrogen isotope is called:
The hydrogen isotope is called:
The hydrogen isotope is called:
The number of neutrons in deuterium is:
The number of neutrons in tritium is:
Isotopes of an element have:
Tritium has mass number:
The atomic mass of copper is:
The atomic mass of chlorine is:
The reference for relative atomic mass is:
of the mass of one carbon-12 atom equals:
The relative atomic mass has:
The actual mass of an aluminium atom is g. Its relative atomic mass is:
Why is relative atomic mass used instead of actual mass?
The mass of one fluorine atom is given as:
AMU stands for:
The relative atomic mass = (actual mass of one atom) ÷:
To find average relative atomic mass, mass numbers of isotopes are multiplied by their:
After summing the products, divide by:
Natural abundance of is:
Natural abundance of is:
Average relative atomic mass of chlorine equals =
Natural abundance of is:
Natural abundance of is:
The average relative atomic mass shown in the periodic table for Cl is:
The relative molecular mass is the sum of:
Relative molecular mass of is:
Relative molecular mass of is:
Relative molecular mass of is:
Relative molecular mass of is:
Relative molecular mass of is:
Relative molecular mass of is (using H = 1, Cl = 35.5):
Relative molecular mass of is:
Relative molecular mass of (Cl = 35.5) is:
Isotopes whose nuclei spontaneously break and emit rays are called:
Which is NOT a radioactive ray?
About how many isotopes have been discovered so far?
Symbol of alpha rays is:
Symbol of beta rays is:
Symbol of gamma rays is:
Technetium-99 is used to:
The lifetime of Technetium-99 is:
Which isotope is used to cure thyroid cancer?
Brain cancer is treated using:
Which isotope is used to diagnose and treat tumors?
Leukemia is treated using which isotope?
The rays emitted by Technetium-99 used in imaging are:
The rays emitted by that destroy cancer cells are:
Radioactive isotopes help determine the amount of which nutrients in soil?
Which device is used to detect radioactive isotopes in plants?
Excess fertilizer is harmful for the:
Insecticides enriched with radioactive isotopes help to determine the:
Radioactive isotopes also play a role in developing:
Heat used to generate electricity in nuclear power plants is produced by:
Power plants using nuclear reactions are called:
Bangladesh's nuclear power plant is located at:
The capacity of Rooppur nuclear power plant is:
Radioactive rays can cause genetic changes that may lead to:
Atom bombs used in WWII killed people in:
The 1986 Chernobyl accident occurred in:
Three radioactive rays harmful to humans are: