NSD -2025

Across

2. – A state in which the forward and reverse reactions occur at the same rate.
4. – Different structural forms of the same element in the same physical state.
6. – A measure of the disorder or randomness in a system.
7. – A solution that resists changes in pH when an acid or base is added.
9. – Atoms of the same element with different numbers of neutrons.
11. – The substance in which the solute dissolves to form a solution.
14. – The calculation of reactants and products in a chemical reaction.
18. – A substance that undergoes change in a chemical reaction.
20. – An element that lacks metallic properties and is usually a poor conductor.
21. – An element with properties intermediate between metals and nonmetals.
22. Forces – Forces of attraction between molecules, including dipole-dipole, hydrogen bonding, and dispersion forces.
24. – An atom or molecule with a net electric charge due to the loss or gain of electrons.
25. – A substance that increases the concentration of hydroxide ions (OH⁻) in a solution.
28. Bond – A bond formed between oppositely charged ions due to electron transfer.
32. Solution – A solution in which no more solute can dissolve at a given temperature.
33. Chatelier’s Principle – The principle stating that a system at equilibrium will adjust to counteract changes in conditions.
34. Solution – A solution that contains more dissolved solute than it can normally hold at a given temperature.
35. Reactant – The reactant that determines the amount of product formed in a reaction.
37. – The time required for half of a radioactive substance to decay.
38. Reaction – A reaction that releases heat into its surroundings.
39. – The total heat content of a system.
41. (M) – The concentration of a solution expressed as moles of solute per liter of solution.
42. – The loss of electrons by an atom or molecule.
44. – The gain of electrons by an atom or molecule.
45. – A substance that speeds up a chemical reaction without being consumed.
46. – A substance made of only one type of atom.
47. – The smallest unit of an element that retains its chemical properties.
49. Reaction – A chemical reaction involving both oxidation and reduction.

Down

1. – A technique used to determine the concentration of a solution by reacting it with a standard solution.
3. Number – The sum of protons and neutrons in an atom’s nucleus.
4. Number – the number of particles in one mole of substance.
5. – A substance formed as a result of a chemical reaction.
8. – The ability of an atom to attract electrons in a chemical bond.
10. Reaction – A reaction that absorbs heat from its surroundings.
12. – A group of two or more atoms chemically bonded together.
13. Properties – Properties of solutions that depend on the number of solute particles, such as boiling point elevation and freezing point depression..
15. Number – The number of protons in an atom’s nucleus.
16. Bond – A chemical bond formed by the sharing of electron pairs between atoms.
17. – The mixing of atomic orbitals to form new hybrid orbitals.
19. – A substance that increases the concentration of hydrogen ions (H⁺) in a solution.
23. – The spontaneous emission of radiation by an unstable atomic nucleus.
26. – The substance dissolved in a solution.
27. – An insoluble solid that forms in a solution during a chemical reaction.
29. – A substance composed of two or more different elements chemically bonded together.
30. Yield – The ratio of actual yield to theoretical yield expressed as a percentage.
31. – A homogeneous mixture of solute and solvent.
36. Free Energy – A thermodynamic quantity indicating the spontaneity of a reaction.
40. – A measure of the acidity or basicity of a solution on a scale of 0-14.
43. – An element that is a good conductor of heat and electricity, malleable, and ductile.
48. – The SI unit for the amount of substance, containing Avogadro’s number of particles.