The main detector planned for the India-based Neutrino Observatory in Theni district is

The correct answer is C, 27 km. The Large Hadron Collider occupies a circular tunnel about 27 kilometres around, lying roughly 100 metres below the ground on the Swiss-French border near Geneva, and it is the largest and most powerful particle accelerator ever built; the tunnel was originally dug for an earlier CERN machine, the Large Electron-Positron collider. Option A, 7 km, is far too small and is nearer the size of a medium accelerator ring. Option B, 17 km, is a popular distractor because the number is close, and candidates who remember only that the figure is in the twenties often pick it. Option D, 47 km, is larger than the LHC and is the kind of figure discussed for proposed future colliders, not for the existing machine. Remember the pair 27 km and 100 m deep, and that the protons inside are steered by superconducting magnets cooled with liquid helium.

The correct answer is A, Geneva. The European Organization for Nuclear Research, founded in 1954, has its campus at Meyrin on the outskirts of Geneva in Switzerland, and because its tunnels run under the border, parts of the laboratory lie in France as well. Option B, Vienna, is the seat of the International Atomic Energy Agency, which is a very different body dealing with nuclear safety and safeguards. Option C, Darmstadt in Germany, is the home of the GSI laboratory and of FAIR, the Facility for Antiproton and Ion Research, in which India is a partner, so it belongs to the same family of questions but not to CERN. Option D, Grenoble in France, hosts the European Synchrotron Radiation Facility and the Institut Laue-Langevin. A quick memory link is CERN, Geneva, 1954 and the 27-kilometre ring.

The correct answer is B, ATLAS and CMS. These are the two general purpose detectors on the LHC ring, and in July 2012 both independently reported a new particle of about 125 giga-electronvolts that matched the Higgs boson, the particle linked to the field that gives mass to other particles; the Nobel Prize in Physics of 2013 went to Peter Higgs and Francois Englert for the theory. Option A, ALICE and LHCb, are also LHC experiments, but ALICE studies the quark-gluon plasma in heavy-ion collisions and LHCb studies particles containing the bottom quark. Option C, Super-Kamiokande in Japan and SNO in Canada, are neutrino detectors whose work on neutrino oscillation won the Nobel Prize of 2015. Option D names the detector and the readout chambers planned for the India-based Neutrino Observatory, not anything at CERN. The word boson itself honours Satyendra Nath Bose.

The correct answer is C, France. ITER is coming up at Saint-Paul-les-Durance in the Cadarache area of southern France, and its seven partners are the European Union, China, India, Japan, Russia, South Korea and the United States; the name is the Latin word for the way. Option A, Japan, is a partner and hosts related fusion work under a broader approach agreement with Europe, including the JT-60SA tokamak, which is why it is a tempting answer, but the ITER machine itself is in France. Option B, Germany, runs the Wendelstein 7-X stellarator at Greifswald, a different kind of magnetic confinement device. Option D, the United States, is a partner and earlier hosted major tokamaks such as TFTR, but not ITER. Fix in mind the chain ITER, tokamak, Cadarache in France, India in since 2005.

The correct answer is A, the Institute for Plasma Research at Gandhinagar. This institute of the Department of Atomic Energy is the national centre for plasma and fusion research, it houses the domestic agency ITER-India that supplies India share of the machine, and it operates India own tokamaks Aditya and SST-1, the Steady State Superconducting Tokamak. Option B, the Bhabha Atomic Research Centre, is the premier centre for fission reactors, radioisotopes and the nuclear fuel cycle, not the ITER domestic agency. Option C, the Indian Institute of Astrophysics, works on telescopes and solar physics and is associated with projects such as the Thirty Meter Telescope. Option D, the Physical Research Laboratory, is the cradle of Indian space research and works on planetary and atmospheric sciences. The link to remember is plasma and fusion mean Gandhinagar.