Question Library

u = 5 cm , f = 10 cm, v = ? (1)/v + (1)/u = (1)/f (1)/v + (1)/5 = (1)/10 = (1)/v = (1)/10 - (1)/5 = (1 - 2)/10 = (1)/10 ∴ v = - 10 cm ∴ The image is 10 cm behind the mirror

Sin c = (1)/n = (1)/1.51 = 0.6622 ∴ c = sin-\(^1\) 0.6622 = 41.47

The speed of sound is highest in solid. Metals (solids) like copper, steel rod, etc

The quality of a note is a characteristic that distinguishes it from note of the same frequency played by another musical instrument.

VELOCITY=DISTANCE/TIME Distance = 330\times5.8 Distance = 1914m

Accommodation is the adjustment of the optics of the eye to keep an object in focus on the retina as its distance from the eye varies.

Sulfur is insoluble in water but sugar is soluble. Hence; dissolution of sugar to have sulfur as the only insoluble solid. Filtration: The filtrate is the liquid that passes through the filtration filter. Meanwhile, the residue is the solid that remains on the filtration filter. Evaporation: water as part of the filtrate changes into a gas to leave sugar as residue.

Freezing is a physical change. It involves a liquid changing states to a solid. Thus, freezing a substance will not change its chemical identity, but its state.

molar mass of water [7H\(_2\)O] = 7[ 2 * 1 + 16] → 7 * 18 = 126g/mol molar mass of ZnSO\(_4\).7H\(_2\)O = [65 * 1] + [32 * 1] + [16 * 4] + 7[ 2 * 1 + 16] → 65 + 32 + 64 + 126 = 287g/mol percentage of water of crystallization = \(\frac{mass of water of crystallization}{mass of hydrated compound} * 100%\) → \(\frac{126}{287} * 100\) = 43.9 ≈ 44%

1mole of gas at STP = 22.4dm\(^3\) 0.0075 mole of CaCO3 = xdm\(^3\) cross multiply; where 22.4dm\(^3\) = 22400cm\(^3\) x * 1 = 0.0075 * 22400 → 168cm\(^3\) the gas CO2 which evolved was gotten from CaCO3 so we use the number of moles of CaCO3 only

Sodium has atomic / proton number of 11 and belongs to Group 1[alkali metals] on the periodic table

The principal quantum number, n, describes the energy of an electron and the most probable distance of the electron from the nucleus. In other words, it refers to the size of the orbital and the energy level an electron is placed in. The azimuthal quantum number is a quantum number for an atomic orbital that determines its orbital angular momentum and describes the shape of the orbital.

\({Cu(NH_3)_4}^2\)+: The bonding in this ion consists of coordinate covalent bonds with all bonding electrons supplied by the nitrogen atom.

Potassium dichromate, K\(_2\)Cr\(_2\)O\(_7\) → [1 * 2] + [Cr * 2] + [-2 * 7] = 0 → 2 + 2Cr - 14 = 0 → 2Cr = 12 →Cr = \(\frac{12}{2}\) → 6

Gas pressure is the name given to the force exerted by gas particles colliding with the wall of their container.