Structure of the Atom

The mass of an atom is located in its:

Which of the following describes a neutron?

In a neutral atom, if the number of electrons is 11, the number of protons must be:

The symbol for a proton is usually written as:

Which of the following describes the charge of an electron?

Canal rays move in a direction:

If an atom has 11 protons and 12 neutrons, what is the number of electrons in its neutral state?

Which experiment led to the discovery of the nucleus?

What happens to the mass of an atom if two neutrons are added and one proton is removed?

Which of the following is true for an element with atomic number 17 and mass number 35?

Which experiment disproved the Thomson model?

What is the charge on the nucleus of an atom?

In Thomson's model, the atom is a sphere of:

What happens to the speed of alpha particles as they pass very far from the nucleus?

Why are $\alpha$-particles deflected when they come near the nucleus?

What would be the charge of a nucleus if it contained 6 protons?

Which of these features is common to both Thomson's and Rutherford's models?

What happens to the kinetic energy of an $\alpha$-particle as it approaches the nucleus head-on, just before it rebounds?

If an $\alpha$-particle is deflected by $90^{\circ}$, what does this imply about its path relative to the nucleus?

The $\alpha$-particles used in the experiment are essentially which of the following?

According to Bohr's model, atoms are stable because electrons:

The name of the scientist who helped Bohr develop the rules for electron distribution was:

What is the electronic configuration of Magnesium (Atomic number 12)?

Bohr's model proposed that electrons revolve around the nucleus in fixed orbits. These orbits are:

The electronic configuration 2, 1 represents which of the following elements?

According to Bohr's model, the energy of the shells ______ as the distance from the nucleus increases.

What is the electron distribution in a Sulfur atom ($Z=16$)?

Which shell transition requires the most energy absorption for an electron starting in the $K$ shell?

In the context of Bohr's model, what does the term 'discrete' imply about electron orbits?

What is the valency of an element whose $K$ and $L$ shells are full and $M$ shell has 2 electrons?

James Chadwick's discovery of the neutron helped explain why:

The number of neutrons in the nucleus of an atom of Chlorine-37 is:

If an atom has 1 neutron and 1 proton, it is an isotope of:

Which of these subatomic particles is found inside the nucleus but has no charge?

Which statement is false regarding neutrons?

In the atom of Carbon-12, the number of protons, neutrons, and electrons are respectively:

An atom has 10 protons and a mass number of 20. Another atom has 10 protons and a mass number of 22. These two atoms are:

In the discovery of neutrons, James Chadwick used beryllium because it has a relatively high concentration of neutrons. What is the neutron count in a standard beryllium atom ($^9_4Be$)?

Which subatomic particle has the least contribution to the total mass of an atom?

An element has $18$ neutrons and its mass number is $35$. Which group of the periodic table does this element belong to?

What is the valency of Boron ($B$) with atomic number 5?

An atom that loses 2 electrons to achieve stability has a valency of:

Which element has a valency of 1 and is a non-metal?

What is the valency of an atom with 2 electrons in the $K$ shell and 5 electrons in the $L$ shell?

Potassium ($Z=19$) and Sodium ($Z=11$) both have a valency of 1 because:

An element with atomic number 10 is Neon. Why is its valency zero?

What is the valency of Oxygen in $CO_2$?

Element $X$ has 17 protons. Element $Y$ has 11 protons. They combine to form a compound. What is the valency of $X$ and $Y$ in the compound respectively?

Identify the valency of the element $Y$ which is an isobar of Calcium (Atomic Number 20) and has 22 neutrons.

An atom has 2 electrons in $K$ shell, 8 in $L$ shell and 8 in $M$ shell. If it loses two electrons, what will be its valency in the ionic state?

An element $X$ has 13 protons. To which group does it belong?

What is the atomic number of Fluorine?

The mass number of an atom is mostly concentrated in the:

Which element has atomic number 1?

What is the common feature between $^{14}_{6}C$ and $^{14}_{7}N$?

Oxygen has an atomic number of 8 and a mass number of 16. How many nucleons does it have?

The number of electrons in an element $X$ is 15 and the number of neutrons is 16. Which of the following is the correct representation of the element?

If an element has atomic number 16 and mass number 32, how many electrons are in its M shell?

Which set of subatomic particles defines the chemical identity of an element?

An element $A$ has atomic number 7. What is the number of electrons in the $A^{3-}$ ion?

How many protons does the isotope Tritium ($_{1}^{3}H$) have?

Isobars are atoms of different elements. This statement is:

The total number of protons in isotopes of the same element is:

Isotopes are used in medicine. Which isotope is used to check the functioning of the thyroid gland?

Study the information provided in the flowchart regarding two different atoms, $X$ and $Y$. If these two atoms are known to be isobars, what is the total number of neutrons in the nucleus of atom $Y$?

Identify the isotope used for treating goitre.

Which statement about Protium and Deuterium is correct?

Which isotope is used to determine the age of very old organic objects?

Chlorine-35 and Chlorine-37 are isotopes. How many neutrons are in Chlorine-37?

An element $M$ has an atomic mass of $24.3\,u$. It has two isotopes $^{24}M$ and $^{25}M$. The percentage of $^{24}M$ in the sample is:

In Rutherford's experiment, the foil used was made of gold primarily because it is highly:

The existence of a heavy, positively charged center in an atom was proven by:

Thomson's model compared the atom to which of the following desserts?

Rutherford's atomic model is also known as:

Based on Bohr's atomic model, consider Element $P$ with an atomic number ($Z$) of 15 and Element $Q$ whose electron distribution is shown in the diagram. Which of the following statements correctly compares these two elements?

The gold foil experiment showed that the nucleus has a ________ radius and a ________ mass compared to the rest of the atom.

Rutherford's model was considered incomplete because it couldn't explain why atoms are:

Which of the following conclusions can be drawn from the fact that most $\alpha$-particles passed through the gold foil undeflected?

Rutherford's model proposed that electrons revolve in orbits. This was a significant departure from Thomson's model because:

What happens to the velocity of an $\alpha$-particle as it approaches a gold nucleus head-on?

What is the valency of an element with 17 protons?

An atom with 8 valence electrons is said to have a/an:

Which element has 3 valence electrons?

The number of electrons lost or gained by an atom to complete its octet is called its:

An element's atom has its electrons distributed in two shells, K and L. The L-shell, which is the outermost shell, contains 6 electrons. Based on this electronic distribution as represented in the diagram, what is the valency of the element?

In the flowchart below, the arrow from Atom $X$ to Atom $Y$ indicates that they are isotopes, and the arrow from Atom $Y$ to Atom $Z$ indicates that they are isobars. Based on this relationship, which of the following sets of atomic numbers ($Z$) and mass numbers ($A$) is correct?

How many electrons are needed by an atom with 6 protons to complete its octet, and what is its valency?

An element has isotopes with mass numbers 10 and 12. If the average atomic mass is 10.2, what is the percentage of the heavier isotope?

An atom has 20 protons and 20 neutrons. Its isotope has 22 neutrons. What is the mass number of the isotope?

Which of the following correctly describes the relationship between the number of neutrons and protons in an isotope compared to an isobar?

Boron-10 and Boron-11 are isotopes. How do they differ?

Which of the following atoms has 6 neutrons and 5 protons?

If you subtract the number of protons from the mass number, you get the number of:

Sulfur has atomic number 16 and mass number 32. How many neutrons are present?

A neutral atom of Oxygen ($Z = 8$) has a mass number ($A$) of 17. As illustrated in the transition diagram below, the atom gains two electrons to form an oxide ion ($O^{2-}$). How many neutrons are located in the nucleus of the resulting ion?

If an atom's mass number is doubled but the atomic number stays the same, which particle count must have increased?

The charge-to-mass ratio ($e/m$) of a neutron is:

The number of neutrons in $^{235}_{92}U$ is:

An atom has 14 protons and 14 neutrons. What is its mass number?

If the number of neutrons in an atom is 12 and its atomic number is 11, the atom is:

In the notation $_6^{12} C$, what does the number 12 represent?

Which shell is filled first in an atom?

What is the atomic number of Carbon?

If an atom has 8 protons and 8 electrons, what is the net charge on the atom?

If J.J. Thomson's 'Plum Pudding' model of the atom—which proposed that positive charge and mass are uniformly distributed—had been correct, what would have been the expected outcome of Rutherford's $\alpha$-particle scattering experiment?

In the study of atomic structure, E. Goldstein used a modified discharge tube with a perforated cathode. He observed radiation (canal rays) moving in the direction opposite to cathode rays. Which of the following statements correctly describes a unique property of these canal rays compared to cathode rays?

Which postulate of Dalton’s atomic theory is the result of the law of conservation of mass?

An element has an atomic number 12 and mass number 26. How many neutrons and protons does it have?

If an atom has 8 electrons in its $M$ shell and it is the outermost shell, what is the atomic number of the element?

What is the mass of one mole of electrons approximately?

According to the CBSE Grade 9 curriculum, which model is often compared to a Christmas pudding?

Which of the following elements has the same number of protons, neutrons, and electrons?

What is the valency of Neon (Atomic number = 10)?

An alpha particle is basically a nucleus of which element?

According to the historical Bohr model of the atom, electrons move between discrete orbits by gaining or losing energy. If an electron transitions from the $L$ shell ($n = 2$) to the $K$ shell ($n = 1$), which of the following correctly describes the energy change?

Which isotope is used in the treatment of goitre (a thyroid condition)?

Which subatomic particle's discovery was the last among the three main particles?

Which scientist's model was the first to propose that electrons move in specific, fixed paths or orbits?

Isotopes like Deuterium and Tritium differ in their number of:

Which of the following statements about 'Energy Shells' is correct according to Bohr?

Who suggested that electrons revolve around the nucleus in fixed orbits?

What is the electronic configuration of Sodium (Atomic number 11)?

Which subatomic particle is the lightest?

The first shell to be filled in an atom is:

Calculate the average atomic mass of an element $X$ which exists as 75% of $^{35}X$ and 25% of $^{37}X$.

Which of the following is used as fuel in nuclear reactors?

If the valency of Carbon is 4 and Oxygen is 2, what is the structure of $CO_2$ based on octet sharing?

What is the total number of electrons in a molecule of water ($H_{2}O$)?

Two elements $P$ and $Q$ have the same number of nucleons but different number of protons. They are called:

The number of electrons in an element $X$ is 15 and the number of neutrons is 16. Which of the following is the correct representation of the element?

Which of the following is the symbol for Phosphorus?

What is the symbol for Iodine?

The symbol for the element Cadmium is:

Identify the symbol for the element Arsenic.

The symbol '$O$' represents Oxygen. What is the symbol for Osmium?

Which of these is the correct symbol for Platinum?

The symbol '$Ar$' is for Argon. What is the symbol for Arsenic?

Which of the following symbols is used for 'Copper'?

An atom has 8 protons and 10 electrons. What is its correct symbolic representation?

The symbol '$Na$' for Sodium comes from 'Natrium'. In which ancient language was this name primarily used?

The total number of protons in an atom is its __________.

Which of these elements has the lowest atomic number?

What is the atomic number of Nitrogen?

If an atom has 10 protons, what is the name of the element?

The mass number ($A$) of an atom represents the sum of protons and neutrons in its nucleus. If an atom has a mass number of 31 and contains 16 neutrons, what is its atomic number ($Z$) according to the logic provided in the flowchart?

An atom of element $X$ forms a cation $X^{3+}$ by losing three electrons. If the resulting $X^{3+}$ ion is found to have 10 electrons, what is the atomic number ($Z$) of element $X$ based on the relationship shown in the diagram?

The maximum number of electrons that can be accommodated in the $L$ shell is 8. If an atom's atomic number is 10, the $L$ shell is:

Observe the progression in the diagram. If the sequence represents atoms of consecutive elements, which particle's increment directly defines the shift from A to B to C?

An element $X$ forms an oxide $X_2O_3$. If the atomic number of $X$ is between 10 and 20, what is $X$?

A certain ion $M^{3+}$ has 10 electrons and 14 neutrons. What is the atomic number and mass number of the neutral atom $M$?

The mass number of an element is 7. If it has 3 protons, how many neutrons does it have?

Identify the mass number of $_{18}^{40}Ar$:

Which statement about mass number is correct?

The mass number of an atom is 27 and its atomic number is 13. How many electrons are in the neutral atom?

An atom has a mass number of 32 and 16 neutrons. How many protons does it have?

What is the difference in mass numbers of ${}^{12}_{6}\text{C}$ and ${}^{14}_{6}\text{C}$?

Calculate the mass number of an element with 13 protons and 14 neutrons.

An element $X$ forms a divalent cation $X^{2+}$ that contains $18$ electrons. In the nucleus of a neutral atom of $X$, the number of neutrons is $2$ more than the number of protons. If element $Y$ is an isotope of $X$ and contains one additional neutron compared to the neutral atom of $X$, what is the mass number of element $Y$?

An element $X$ has mass number $40$ and contains $21$ neutrons. What is the electronic configuration of $X^{+}$ ion?

Bromine has two isotopes ${}^{79}_{35}Br$ and ${}^{81}_{35}Br$ in equal proportions. What is the average atomic mass of Bromine?

An element with 7 valence electrons belongs to which group commonly?

How many electrons are in the M shell of Sulphur ($Z=16$)?

What is the configuration for Beryllium ($Z=4$)?

Which of these elements has a full K shell and a half-full L shell?

The valence shell of Magnesium ($Z=12$) is:

How many electrons are in the $M$ shell of Aluminum ($Z=13$)?

Which of these electronic distributions is not possible according to the rules?

Which rule states that the shells are filled in a stepwise manner?

An element $A$ has atomic number 12 and $B$ has atomic number 17. What is the electronic configuration of $A$ and $B$ respectively?

What is the electronic configuration of a Helium atom?

The valency of an atom with 1 valence electron is:

Which of the following is the correct formula to find valency if the number of valence electrons $(n)$ is greater than 4?

An atom has 2 electrons in the K shell and 8 electrons in the L shell. Its valency is:

How many electrons are in the outermost shell of an atom with atomic number 15?

Study the electronic configurations of the four atoms shown in the diagram below. Identify the pair of atoms that possess the same combining capacity (valency) despite having a different number of electrons in their outermost shell.

The following diagram lists the electronic configurations of three distinct elements: $X$, $Y$, and $Z$. Calculate the sum of their respective valencies ($Valency_{X} + Valency_{Y} + Valency_{Z}$) based on their ability to achieve a stable octet.

The valency of Fluorine ($Z=9$) is 1. This is because it:

A metal $M$ has a valency of 3 and a non-metal $X$ has a valency of 2. What is the formula of the compound formed between $M$ and $X$?

An element $X$ forms an ion $X^{3-}$. If the ion has 18 electrons, what is the valency of the element $X$?

An atom has 2 electrons in $K$ shell, 8 in $L$ shell, and 3 in $M$ shell. If it loses all $M$ shell electrons, what is its new valency status?

The number of electrons in a neutral atom is always equal to its:

Which of the following is true for Isotopes?

If an atom has 8 protons and 10 neutrons, its mass number is:

Which particle is represented as $_{-1}^{0}e$?

In the symbol $_{11}^{23}Na$, the number 23 represents the:

Identify the element having 18 protons and 22 neutrons.

Which of these shells has the lowest energy level in an atom?

What is the charge on the nucleus of an atom of Nitrogen ($Z=7$)?

If an atom has 0 valency, it is likely to be:

Which of the following statements about isotopes of Hydrogen is true?