Which ion has negative charge? A. Cation B. Anion C. Proton D. Neutron Explanation: Anions gain electrons.
Which acid turns blue litmus red? A. Base B. Neutral C. Acid D. Salt Explanation: Acids change litmus color.
Which process converts solid to gas? A. Melting B. Sublimation C. Condensation D. Freezing Explanation: Direct phase change solid→gas.
Which law relates heat and temperature? A. Boyle B. Newton cooling C. Ohm D. Coulomb Explanation: Cooling rate proportional to temp difference.
Which metal is best conductor? A. Iron B. Copper C. Silver D. Gold Explanation: Silver has highest conductivity.
Which wave is longitudinal? A. Light B. Sound C. X-ray D. Gamma Explanation: Sound waves are longitudinal.
Which device measures pressure? A. Thermometer B. Barometer C. Voltmeter D. Ammeter Explanation: Barometer measures atmospheric pressure.
Which unit measures force? A. Joule B. Newton C. Watt D. Pascal Explanation: Newton is SI unit of force.
Which force acts between masses? A. Electric B. Magnetic C. Gravitational D. Nuclear Explanation: Gravity acts on mass.
Which layer has auroras? A. Troposphere B. Stratosphere C. Thermosphere D. Mesosphere Explanation: Auroras occur in ionosphere region.