NSD -2025

2. A technique used to determine the concentration of a solution by reacting it with a standard solution.
5. The spontaneous emission of radiation by an unstable atomic nucleus.
7. A substance that undergoes change in a chemical reaction.
10. A state in which the forward and reverse reactions occur at the same rate.
11. The smallest unit of an element that retains its chemical properties.
12. A substance formed as a result of a chemical reaction.
17. A substance that increases the concentration of hydroxide ions (OH⁻) in a solution.
19. The loss of electrons by an atom or molecule.
21. A substance composed of two or more different elements chemically bonded together.
24. A substance made of only one type of atom.
25. An insoluble solid that forms in a solution during a chemical reaction.
27. Different structural forms of the same element in the same physical state.
28. The substance in which the solute dissolves to form a solution.
29. A solution that resists changes in pH when an acid or base is added.

1. The mixing of atomic orbitals to form new hybrid orbitals.
3. An element that is a good conductor of heat and electricity, malleable, and ductile.
4. A group of two or more atoms chemically bonded together.
6. The gain of electrons by an atom or molecule.
8. The substance dissolved in a solution.
9. An atom or molecule with a net electric charge due to the loss or gain of electrons.
11. A substance that increases the concentration of hydrogen ions (H⁺) in a solution.
13. The calculation of reactants and products in a chemical reaction.
14. The concentration of a solution expressed as moles of solute per liter of solution.
15. The SI unit for the amount of substance, containing Avogadro’s number of particles.
16. A measure of the disorder or randomness in a system.
18. A homogeneous mixture of solute and solvent.
20. A substance that speeds up a chemical reaction without being consumed.
22. The total heat content of a system.
23. An element with properties intermediate between metals and nonmetals.
26. Atoms of the same element with different numbers of neutrons.