Level 1
Periodic Table MCQs set 3 for PPSC Food Inspector (BS-14) Everyday Science — 20 solved questions.
Q1. Xenon is heavy among noble gases yet it can form compounds under special lab conditions unlike earlier textbook oversimplifications but it still belongs in Group 18 because of its filled valence octet in simple Lewis teaching. Compared with krypton in the same group xenon atoms are usually described as what?
Answer: Larger with more electron shells down the group trend
Explanation: Atomic radius increases down a group because each successive element has one more electron shell, increasing the distance between the nucleus and outermost electrons; xenon (period 5) is therefore larger than krypton (period 4).
Q2. Lead pipes and weights remind students that heavy elements exist but for grouping lead Pb is most commonly placed in which block region in standard long-form charts?
Answer: p-block main group toward the bottom right of the table in typical charts
Explanation: Lead (Pb) has the electron configuration ending in 6p², placing it firmly in the p-block of the periodic table among the main-group elements in period 6. It sits in Group 14 toward the lower right of the main-group section, far from the s-block alkali metals or the f-block lanthanides.
Q3. A Karachi chemistry tutor asks who turned scattered element notes into periodic gaps that later elements filled like missing puzzle slots. Classroom priority usually awards systematic periodic-law credit with predictive gaps narratives to whom?
Answer: Dmitri Ivanovich Mendeleev
Explanation: Dmitri Mendeleev published his periodic table in 1869, arranging elements by atomic mass and leaving deliberate gaps for undiscovered elements whose properties he predicted; subsequent discoveries of gallium, scandium, and germanium closely matched his forecasts, validating the periodic law.
Q4. The chemical symbol Na stands for which element?
Answer: Sodium
Explanation: The symbol Na derives from the Latin word Natrium; sodium is a Group 1 alkali metal with atomic number 11, essential for nerve impulse transmission and fluid balance.
Q5. Which element has the highest electronegativity on the periodic table?
Answer: Fluorine
Explanation: Fluorine sits at the top-right of the periodic table with the highest effective nuclear charge relative to its atomic radius; on the Pauling scale it has an electronegativity of 3.98, the highest of any element.
Q6. What is the chemical symbol for Iron?
Answer: Fe
Explanation: Iron's chemical symbol Fe derives from the Latin "ferrum"; its atomic number is 26 and it is the most abundant element by mass in Earth's core, playing a central role in steel production.
Q7. Noble gases are chemically inert because they have:
Answer: Complete outer electron shells
Explanation: Noble gases (Group 18) have a full complement of electrons in their outermost shell - two for helium and eight for all others - leaving no unfilled orbitals to form bonds. This stable electron configuration gives them extremely low chemical reactivity under ordinary conditions.
Q8. Which element is liquid at room temperature among the halogens?
Answer: Bromine
Explanation: Bromine (Br) is the only halogen that is a liquid at standard room temperature and pressure (melting point −7 °C, boiling point 59 °C); fluorine and chlorine are gases while iodine is a solid under these conditions.
Q9. What is the atomic number of Sodium (Na)?
Answer: 11
Explanation: Sodium (Na) has 11 protons in its nucleus, giving it atomic number 11; it sits in Period 3, Group 1 of the periodic table. Its single outer-shell electron is readily lost to form the Na⁺ ion, making sodium a highly reactive metal.
Q10. Which group of the periodic table contains the alkali metals?
Answer: Group 1
Explanation: Group 1 elements (lithium through francium) are the alkali metals; each has one valence electron that is easily donated, making them the most reactive metals and causing vigorous reactions with water.
Q11. What is the chemical symbol for Mercury?
Answer: Hg
Explanation: Mercury's chemical symbol Hg derives from the Latin and Greek name "Hydrargyrum," meaning liquid silver, reflecting its unique property of being a metal that is liquid at room temperature. The symbol is one of several in the periodic table inherited from classical names rather than modern language names.
Q12. What is the atomic number of Hydrogen?
Answer: 1
Explanation: Hydrogen has atomic number 1, meaning its nucleus contains exactly one proton; it is the lightest and most abundant element in the universe and the simplest atom.
Q13. Which element has the atomic number 79?
Answer: Gold
Explanation: Gold (Au) has atomic number 79, meaning it has 79 protons. Its chemical symbol Au comes from the Latin word "aurum." Lead has atomic number 82, silver 47, and platinum 78.
Q14. What is the chemical symbol for Silver?
Answer: Ag
Explanation: Silver's chemical symbol Ag comes from the Latin "argentum"; its atomic number is 47 and it has the highest electrical conductivity of all elements, making it valuable in electronics and jewellery.
Q15. Which element is represented by the symbol K?
Answer: Potassium
Explanation: Potassium's symbol K derives from "Kalium," its Latin/German name; it is an alkali metal in Group 1 of the periodic table, essential for nerve impulse transmission and muscle contraction.
Q16. Which is the most reactive group of metals on the periodic table?
Answer: Alkali metals
Explanation: Alkali metals (Group 1) have the lowest ionization energies of any group; their single valence electron is lost extremely easily, making them more reactive than transition metals, alkaline earth metals, or the corrosion-resistant noble metals.
Q17. What is the chemical symbol for Lead?
Answer: Pb
Explanation: Lead's chemical symbol Pb comes from its Latin name "plumbum," the same root that gives us the word "plumber," as lead pipes were widely used in ancient Roman water systems.
Q18. What is the atomic number of Calcium?
Answer: 20
Explanation: Calcium has 20 protons, giving it atomic number 20, and is located in Period 4, Group 2 (the alkaline earth metals) of the periodic table. It is the most abundant metal in the human body, essential for bone structure, muscle contraction, and nerve signalling.
Q19. In the periodic table, elements in the same vertical column are called a:
Answer: Group
Explanation: In the periodic table, a vertical column is called a group (or family); elements in the same group have the same number of valence electrons and therefore similar chemical properties, while a horizontal row is called a period.
Q20. How many periods are there in the modern periodic table?
Answer: 7
Explanation: The modern periodic table has 7 horizontal rows called periods, corresponding to the 7 principal energy levels (electron shells) occupied by elements currently known.