Do you ever have a hunch a a number of selection reply is true, however then can by no means show it’s? Don’t fear, Matrix is right here to assist! On this publish, we provide the 2016 HSC Chemistry Paper labored options for a number of selection. It’s one factor to know what the reply is, it’s way more necessary that you recognize why it’s proper.
Learn on and be taught why you bought it proper or fallacious, so you may get it proper each time!
|1||D||The compound is chloroethene, also called vinyl chloride (the monomer from which PVC is made).|
|2||D||Sodium is just not a heavy steel because it is without doubt one of the lightest metals (ingredient 11, mass 22.99). It’s naturally discovered within the surroundings in excessive concentrations with out toxicity for a lot of organisms e.g. in seawater.|
|3||C||You possibly can decide the components by drawing out the total construction and counting the atoms.|
|4||C||Polystyrene could be very stiff, so it’s utilized in screwdriver handles. Plastic luggage are often made from polyethylene.|
|5||B||Water and ethanol can take part in hydrogen bonding with one another. Hydrogen bonds type between a lone pair on a fluorine, oxygen or nitrogen atom, and a hydrogen atom covalently bonded to a fluorine, oxygen or nitrogen atom.
Word: Many faculties will penalise you when you discuss with hydrogen bonding as “bonding”, since it’s thought of an intermolecular drive slightly than a “true” chemical bond.
|6||A||Equimolar means containing the identical variety of moles.
Acetic acid is a monoprotic acid whereas barium hydroxide accommodates two hydroxide ions (proton acceptors) per unit, subsequently they react in a 2:1 ratio and there shall be extra barium hydroxide (a robust base) left over.
Acetic acid additionally reacts with sodium carbonate in a 2:1 ratio, however sodium carbonate is a weak base, so the ensuing resolution will comprise the identical focus of sodium carbonate because the barium hydroxide resolution, however shall be much less fundamental.
Sulfuric acid is a robust diprotic acid, so (C) and (D) would produce neutralised mixtures that may be impartial and weakly acidic, respectively.
|7||B||Lemon juice could be purple, potato juice could be yellow. The opposite indicators could be the identical color for each options.|
|8||D||The intention is to check if the water is tough or gentle. Therefore it will be greatest to make use of gentle water (low focus of calcium and magnesium ions. e/g. distilled water) as a management.|
|9||D||Stability the equation so the sum of the highest numbers (mass numbers) are the identical on each side, and the sum of the underside numbers (atomic numbers) are the identical on each side.
X is 42He.
|10||C||A conjugate base accommodates one much less proton.|
|11||D||The halogen substituents ought to be listed alphabetically. The numbers are assigned in response to the primary level of distinction rule (not the bottom sum, though coincidentally this offers the identical reply for this query).|
|12||C||0.01 M HCl has a pH of two. To extend its pH by 2 models, it ought to be diluted 100-fold i.e. from 100 mL to 10000 mL.|
|13||A||Sodium has a vibrant yellow-orange flame take a look at. Sulfate doesn’t produce bubbles when reacted with acid (this might happen with carbonate). The precipitate is BaSO4.|
|14||B||Reducing the quantity causes the equilibrium to shift to the aspect with much less fuel moles i.e. in direction of N2O4 to minimise the disturbance (Le Chatelier’s precept).|
|15||A||W have to be unsaturated, whereas X is saturated. Shorter alcohols are extra soluble in water.|
|16||B||Aluminium and copper is the mix with largest potential distinction (discuss with the Desk of Customary Discount Potentials on the Information Sheet).
(A) = 0.74 V
(B) = 2.02 V
(C) = 0.63 V
(D) = 1.04 V
|17||D||That is an addition polymer because it has a carbon-only spine. Breaking the polymer at each second C-C bond and re-forming the double bonds offers propene as the unique monomer.|
|18||B||HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
n(HCl) = c x V = 0.1 x 0.06 = 0.006 mol
n(NaOH) = c x V = 0.1 x 0.04 = 0.004 mol
NaOH is limiting, HCl is in extra. Since all the different substances within the remaining resolution are impartial, we solely want to take a look at the focus of HCl within the remaining resolution to find out the pH.
n(HCl)extra = 0.006 – 0.004 = 0.002 mol
Complete quantity = 0.06 + 0.04 = 0.1 L
c(HCl) = 0.002 / 0.1 = 0.02 M = c(H+)
pH = -log10[H+] = 1.699 = 1.70 (2 s.f.)
Word: Solely the digits after the decimal level are important for pH. Since it’s an exponential, the integer portion is used to find out the place of the decimal level, which isn’t thought of important.
|19||C||Ba(NO3)3(aq) + Na2SO4(aq) → BaSO4(s) + 2NaNO3(aq)
n(Na2SO4) = c x V = 0.2 x 0.2 = 0.04 mol
n(BaSO4) = 0.04 mol (1:1 mole ratio)
m(BaSO4) = n x MM = 0.04 x (137.3 + 32.07 + 16 x 4) = 9.3348 g = 9.33 g (3 s.f.)
|20||A||In atomic absorption spectroscopy, the depth of sunshine earlier than absorption by the pattern (i.e. on the lamp) is in comparison with the depth after absorption (i.e. on the detector) on the identical wavelength (on this case, 615.2 nm). The opposite choices don’t evaluate intensities on the identical wavelength.|