neco model questions vol1 2019 chemistry | Practical

Prepare for your exams with neco model questions vol1 questions? Reviewing past/model questions is one of the most effective ways to guarantee a high score. This practice hub features authentic 2019 chemistry (Practical) questions designed to simulate the real exam environment.

Practice these randomly selected questions to test your readiness.

Question 1 View Details
A student performed a flame test on three unknown solid samples (A, B and C) using a Bunsen burner. The observed flame colours were recorded as follows: - Sample A: bright crimson - Sample B: intense yellow‑orange - Sample C: pale violet The student also carried out the same test on four reference metal salts whose dominant flame colours are known: - Sodium chloride (NaCl) – bright yellow‑orange - Calcium chloride (CaCl₂) – brick‑red - Potassium chloride (KCl) – pale violet - Strontium chloride (SrCl₂) – bright crimson The student is required to: (a) Identify the metal ion present in each unknown sample by comparing the flame colours with the reference salts. (b) Using the identified metal ion, write the electronic configuration of the outermost (valence) shell for each metal. (c) From the electronic configurations, deduce the group number of each metal in the periodic table and explain how the flame colour is related to the electronic transitions involved.
Question Parts
(a)
Identify the metal ion present in each unknown sample by comparing the flame colours with the reference salts.
(b)
Write the electronic configuration of the outermost (valence) shell for each identified metal.
(c)
From the electronic configurations, deduce the group number of each metal in the periodic table and explain how the flame colour is related to the electronic transitions involved.
Detailed Essay Solution & Marking Scheme Available

Get the step-by-step mathematical proofs, key points required by examiners, and a comprehensive breakdown from our AI Tutor.

Reveal Answer
Question 2 View Details
A student measured the mass and volume of an unknown metallic solid using a graduated cylinder filled with water (water‑displacement method). The recorded data are: - Mass of the metal (m) = 45.0 g - Initial water volume = 30.0 mL - Final water volume after immersion = 35.0 mL The student is provided with the following density data for common metals (in g cm⁻³): | Metal | Density | |-------|---------| | Magnesium (Mg) | 1.74 | | Aluminum (Al) | 2.70 | | Iron (Fe) | 7.87 | | Copper (Cu) | 8.96 | | Zinc (Zn) | 7.14 | | Silver (Ag) | 10.5 | Using the experimental data and the table, the student must: a) Calculate the density of the unknown metal. b) Identify the metal by comparing the calculated density with the given values and justify the choice using periodic‑table trends (period and group). c) Using the atomic mass of the identified metal (Cu = 63.55 g mol⁻¹), calculate the number of moles present in the sample and estimate the total number of atoms (use Avogadro’s number 6.02 × 10²³ mol⁻¹).
Question Parts
(a)
Calculate the density of the unknown metal.
(b)
Identify the metal by comparing the calculated density with the given values and justify the choice using periodic‑table trends (period and group).
(c)
Using the atomic mass of copper (63.55 g mol⁻¹), calculate the number of moles present in the sample and estimate the total number of atoms.
Detailed Essay Solution & Marking Scheme Available

Get the step-by-step mathematical proofs, key points required by examiners, and a comprehensive breakdown from our AI Tutor.

Reveal Answer
Question 3 View Details
A student carried out a series of simple tests on three solid samples labelled X, Y and Z to investigate the nature of the bonding present in each sample. The observations recorded are shown in the table below. | Sample | Solubility in water | Conductivity of aqueous solution | Conductivity of solid (electrode test) | Approx. melting point | |--------|----------------------|-----------------------------------|----------------------------------------|-----------------------| | X | Soluble | Good (bright lamp) | No (no current) | 800 °C | | Y | Insoluble | None (lamp off) | No (no current) | 150 °C | | Z | Insoluble | None (lamp off) | Yes (current observed) | 1085 °C | Using the data above, answer the following questions.
Question Parts
(a)
Identify the type of bonding present in each of the three samples (X, Y and Z).
(b)
Explain why the aqueous solution of sample X conducts electricity well.
(c)
State two physical properties of sample Y from the table that support its classification as a covalent (molecular) solid.
(d)
Suggest one precaution that should be observed when measuring the melting point of sample Z to avoid error.
Detailed Essay Solution & Marking Scheme Available

Get the step-by-step mathematical proofs, key points required by examiners, and a comprehensive breakdown from our AI Tutor.

Reveal Answer
Question 4 View Details
A student performed a gravimetric analysis to determine the purity of an impure sample of copper(II) carbonate (CuCO₃). The procedure was as follows: 1. Accurately weigh 1.500 g of the impure sample and record the mass. 2. Dissolve the sample in dilute hydrochloric acid, precipitating copper(II) carbonate. 3. Filter the precipitate, wash it with de‑ionised water and dry it. 4. Transfer the dried precipitate to a crucible and heat strongly in a muffle furnace until a constant mass is obtained. The heating converts CuCO₃ to copper(II) oxide (CuO) according to: CuCO₃ → CuO + CO₂. 5. The final constant mass of CuO obtained is 0.845 g. Using the data above, answer the following questions.
Question Parts
(a)
Calculate the number of moles of CuO obtained.
Detailed Essay Solution & Marking Scheme Available

Get the step-by-step mathematical proofs, key points required by examiners, and a comprehensive breakdown from our AI Tutor.

Reveal Answer

Master the Exam!

You've seen a preview, but there are thousands more questions plus AI tutor to break down complex solutions.

Unlock Full Access Available for Android & Windows
Help others prepare! Share this practice hub:
Chat with Support