NSMQ 2018 past questions with answers

Answer

C3H8O

1. 1.Assume a 100 g sample so masses are C = 60.0 g, H = 13.3 g, O = 100 g – (60.0 g + 13.3 g) = 26.7 g.
2. 2.Calculate moles: n_C = 60.0 g/12.0 g·mol⁻¹ = 5.00 mol; n_H = 13.3 g/1.0 g·mol⁻¹ = 13.3 mol; n_O = 26.7 g/16.0 g·mol⁻¹ = 1.67 mol.
3. 3.Divide by smallest mole value (1.67 mol): C = 5.00/1.67 = 3.00; H = 13.3/1.67 ≈ 8.00; O = 1.67/1.67 = 1.00, giving C₃H₈O.

Answer

x = -3, 3, 5

1. 1.List possible rational roots using the factors of the constant term 45: ±1, ±3, ±5, ±9, ±15, ±45. Test x=3: 3³−5·3²−9·3+45=27−45−27+45=0, so (x−3) is a factor.
2. 2.Divide the cubic polynomial by (x−3) (using synthetic or long division) to get the quadratic x²−2x−15.
3. 3.Factor the quadratic: x²−2x−15=(x−5)(x+3). Set each factor to zero to find x=5 and x=−3. Combine with the root x=3.

Answer

$2.5\times 10^{-6}{\text{m/s}}^2$

1. 1.Calculate the electric field between the plates using $E=V/d$. Substituting $V=20.0\mathrm{V}$ and $d=0.20\mathrm{m}$ gives $E=100N/C$.
2. 2.Compute the force on the particle using $F=qE$. With $q=5.0\times 10^{-9}\mathrm{C}$, we get $F=(5.0\times 10^{-9}\mathrm{C})(100N/C)=5.0\times 10^{-7}\mathrm{N}$.
3. 3.Find the acceleration from Newton’s second law $a=F/m$. Thus $a=(5.0\times 10^{-7}\mathrm{N})/(0.20\mathrm{kg})=2.5\times 10^{-6}m/{\mathrm{s}}^2$.

Answer

0.130 mol dm⁻³

1. 1.Convert volumes to dm³: V(S₂O₃²⁻)=19.5 cm³=0.0195 dm³, V(I₂)=15.0 cm³=0.0150 dm³.
2. 2.Calculate moles of thiosulfate: n(S₂O₃²⁻)=c×V=0.200 mol dm⁻³×0.0195 dm³=0.00390 mol.
3. 3.Use the 1 : 2 stoichiometry (2 mol S₂O₃²⁻ react with 1 mol I₂) to find n(I₂)=0.00390 mol÷2=0.00195 mol.
4. 4.Determine concentration of iodine: c(I₂)=n/V=0.00195 mol÷0.0150 dm³=0.130 mol dm⁻³.

Answer

45 J

1. 1.Calculate the Lorentz factor: $\gamma =\frac{1}{\sqrt{1-(v/c{)}^2}}=\frac{1}{\sqrt{1-0.6^2}}=1.25$
2. 2.Compute the rest energy: $m{c}^2=(2.0\times 10^{-15}\text{kg})(3.0\times 10^8\text{m/s}{)}^2=1.8\times 10^2\text{J}$
3. 3.Compute the relativistic kinetic energy: $K=(\gamma -1)m{c}^2=(1.25-1)\times 1.8\times 10^2\text{J}=45\text{J}$

Answer

$\frac{43}{99}$

1. 1.Let $x=0.434343\dots$, so $x=0.\overline{43}$.
2. 2.Multiply both sides by 100 to shift the decimal two places: $100x=43.434343\dots$.
3. 3.Subtract the original equation from this: $100x-x=99x=43$, hence $x=\frac{43}{99}$.

Answer

False

Replication doubles chromatids, centromeres stay the same.

Answer

True

Silica gel’s high surface area and microporosity enable it to adsorb water vapor efficiently, making it an effective desiccant for moisture control in packaging.

Answer

Order of operations

Answer

Homopolar generator (Faraday disk dynamo)