Science - Chemistry Questions for SSC MTS

Atomic Structure and Elements

An atom is the smallest unit of matter. It has a nucleus (protons + neutrons) surrounded by electrons in shells. Protons are positive, electrons negative, neutrons neutral. The number of protons defines the element. SSC MTS asks: What is an atom? How many protons in carbon? What is atomic number? Keep it simple — think of an atom like a mini solar system with nucleus as sun and electrons as planets.

• Atomic number = number of protons (defines the element)
• Mass number = protons + neutrons
• Electrons = protons (in neutral atom)
• Valency = number of electrons in outermost shell (or 8 minus that number)
• Isotopes = same element, different neutrons, different mass number

Periodic Table Basics

The periodic table organizes elements by atomic number and properties. Elements in the same vertical column (group) have similar properties because they have the same number of valence electrons. Horizontal rows are periods. SSC MTS focuses on: What are groups and periods? Which elements are metals, non-metals, metalloids? Remember: Left side = metals, right side = non-metals, middle = metalloids.

• Groups (vertical columns) = same valence electrons = similar chemical behavior
• Periods (horizontal rows) = increasing atomic number
• Metals: shiny, conduct heat/electricity, malleable, ductile (left and center)
• Non-metals: dull, poor conductors, brittle (right side)
• Metalloids: semi-conductors, properties between metals and non-metals (boron, silicon, arsenic)

Chemical Reactions and Equations

A chemical reaction is when atoms rearrange to form new substances. Reactants (inputs) become products (outputs). SSC MTS asks: Identify reaction type, balance simple equations, understand combustion/oxidation. Key types: Combination (A+B=AB), Decomposition (AB=A+B), Displacement (A+BC=AC+B), Double displacement (AB+CD=AD+CB). Combustion = burning in oxygen.

• Balanced equation: same number of each atom on both sides
• Combination: two or more substances form one (synthesis)
• Decomposition: one substance breaks into two or more
• Displacement: more reactive element pushes out less reactive one
• Combustion: substance burns in oxygen, releases heat and light
• Oxidation = loss of electrons; Reduction = gain of electrons (OIL RIG)

Acids, Bases, and Salts

Acids taste sour, turn blue litmus red, have pH < 7. Bases taste bitter, turn red litmus blue, have pH > 7. pH 7 is neutral. Salts form when acid reacts with base. SSC MTS asks: Identify acids/bases, what is pH, examples of common acids/bases. Think: Lemon juice = acid (sour), soap = base (slippery).

• Acid: donates H+ ions, pH < 7, turns blue litmus red (HCl, H2SO4, HNO3)
• Base: donates OH- ions, pH > 7, turns red litmus blue (NaOH, KOH, Ca(OH)2)
• pH scale: 0-7 acidic, 7 neutral, 7-14 basic
• Neutralization: Acid + Base = Salt + Water
• Common acids: HCl (hydrochloric), H2SO4 (sulfuric), HNO3 (nitric), CH3COOH (acetic/vinegar)
• Common bases: NaOH (sodium hydroxide), KOH (potassium hydroxide), NH3 (ammonia)

Metals and Non-metals

Metals are elements that lose electrons easily and form positive ions (cations). Non-metals gain electrons and form negative ions (anions). SSC MTS asks: Properties of metals vs non-metals, reactivity series, corrosion. Metals are generally shiny, conduct electricity, and are found on the left of the periodic table. Non-metals are on the right.

• Metals: malleable (can be hammered), ductile (can be drawn into wire), conduct heat and electricity
• Non-metals: brittle, insulators, dull appearance
• Reactivity series (most to least reactive): K, Na, Ca, Mg, Al, Zn, Fe, Cu, Ag, Au
• More reactive metal displaces less reactive metal from its salt
• Corrosion: metal reacts with oxygen/moisture (rust = iron oxide)
• Alloy: mixture of two or more metals (brass = copper + zinc, steel = iron + carbon)

Everyday Chemistry Applications

SSC MTS loves practical chemistry: Why do we use bleach? What is soap? How does baking soda work? These are real-life questions. Bleach kills germs via oxidation. Soap has hydrophobic (water-fearing) and hydrophilic (water-loving) ends, so it traps dirt. Baking soda (sodium bicarbonate) reacts with acid to produce CO2 gas, making cakes rise.

• Bleach (sodium hypochlorite): oxidizing agent, kills bacteria and viruses
• Soap: emulsifier, one end loves water, other loves oil, traps dirt particles
• Baking soda (NaHCO3): reacts with acid, produces CO2 gas (leavening agent)
• Rust prevention: paint, grease, galvanization (zinc coating)
• Water hardness: caused by dissolved calcium and magnesium salts, removed by boiling or ion exchange

• Confusing atomic number with mass number. Atomic number = protons only. Mass number = protons + neutrons. SSC MTS will ask 'How many protons in Carbon-12?' Answer: 6 (atomic number), not 12.
• Forgetting to balance chemical equations. A common trap: writing H2 + O2 = H2O without balancing. Correct: 2H2 + O2 = 2H2O. Always count atoms on both sides.
• Mixing up acids and bases by color. Remember: Acids turn blue litmus RED. Bases turn red litmus BLUE. Reverse order = easy to flip.
• Assuming all metals are magnetic or all non-metals are gases. Iron is magnetic, but copper is not. Oxygen is a non-metal gas, but carbon (diamond) is a non-metal solid.
• Not knowing the reactivity series order. Aspirants memorize randomly. Use mnemonic: 'King Na Ca Mg Al Zin Fe Cu Silver Gold' (K, Na, Ca, Mg, Al, Zn, Fe, Cu, Ag, Au).

• OIL RIG: Oxidation Is Loss (of electrons), Reduction Is Gain. Helps remember redox reactions.
• ACID = Atoms Change In Decomposition. Helps recall that decomposition breaks molecules into simpler parts.
• Litmus trick: Acid = Red (both start with vowel 'A'), Base = Blue (both have 'B'). Reverse for litmus color change.
• Reactivity series mnemonic: 'King Na Ca Mg Al Zin Fe Cu Silver Gold' — top = most reactive, bottom = least reactive.
• pH memory: pH < 7 is acidic (sour like lemon), pH > 7 is basic (bitter like soap), pH = 7 is neutral (pure water).

• SSC MTS Chemistry is 10th-level, not advanced. Expect straightforward questions: 'What is an acid?', 'Name a non-metal', 'Balance this equation'. No complex calculations or deep theory.
• Periodic table questions are rare but possible. Know: metals on left, non-metals on right, groups have similar properties. You won't need to memorize all 118 elements.
• Practical/everyday chemistry is high-frequency. Questions like 'Why does iron rust?', 'How does soap clean?', 'What is bleach used for?' appear regularly. Focus on the 'why', not just the 'what'.
• Acid-base questions often pair with pH scale. Expect: 'Which has pH 2?', 'Identify the base', 'What color does litmus turn?'. Memorize common acids (HCl, H2SO4) and bases (NaOH, KOH).
• Time management: Chemistry questions are quick if you know basics. Spend max 1 minute per question. If stuck, move on — these are not calculation-heavy like Maths.