The UPSC Civil Services Preliminary Examination 2026 is slated for 24 May 2026. With only a few weeks left, candidates should shift from gathering new material to a focused revision of high‑impact science and technology (S&T) topics that have featured in recent current‑affairs. These topics are repeatedly asked in GS‑3 and often intersect with GS‑1 (environment), GS‑2 (policy) and GS‑4 (ethics). A smart, selective review will help you consolidate facts, understand concepts and save valuable time.
Key Topics for Revision
- Sodium‑ion battery: Abundant, cheaper than lithium, can be extracted from seawater, operates at zero‑volt transport, uses aluminium conductors and tolerates higher temperatures.
- Reverse osmosis: Energy‑intensive, generates CO₂ emissions and brine waste; used for desalination, water‑reuse in pharma, biotech and radioactive waste treatment.
- Helioseismology: NASA’s Solar Dynamics Observatory and its Helioseismic and Magnetic Imager track solar oscillations to map internal solar movements.
- Critical minerals: Include lithium, nickel, cobalt, manganese, graphite for batteries and rare‑earths for wind‑turbine magnets; also aluminium and copper for electricity networks.
- CAR T‑cell therapy: Reprograms T‑cells with chimeric antigen receptors to hunt blood cancers such as leukaemia and lymphoma.
- Oort Cloud: Ice debris extending up to 1.6 light‑years; source of long‑period comets and marks the Sun’s gravitational boundary.