Past Questions And Answers
Which of the following acids would form normal salt only?
- A. Tetraoxosulphate(VI) acid
- B. Trioxonitrate(V) acid
- C. Tetraoxophosphate(V) acid
- D. Trioxosulphate(IV) acid
Elements P has an atomic number of 12 while element Q has an atomic number 15. Combination of P and Q gave a compound PmQn. The respective values of m and n are
- A) 2 and 2
- B) 2 and 3
- C) 3 and 2
- D) 2 and 1
Citizens are protected from the government's arbitrariness in taxation by the canon of
- A. elasticity
- B. flexibility.
- C. economy
- D. certainty
A particle that contains 8 proton, 9 neutrons and 7 electrons could be written as?
- A. O
- B. O+
- C. O2+
- D. O-
After the healing of the demaniac in the country of the Gerasenes, the people begged Jesus to
- A. stay with them
- B. visit them always
- C. go away from them
- D. heal their sick
Which of the following isn't used to navigate in a computer?
- A. Cursor
- B. Keyboard
- C. mouse
- D. Scanner
(a) The specific heat capacity of copper is 400 \(JKg^{-1}K^{-1}\) means that 400 J of heat energy is required to raise (or lower) the temperature of 1 kg of a piece of copper by 1 kelvin.
(b) Experiment to determine the specific heat capacity of copper using a copper ball. The piece of copper ball is suspended by a thread and placed in a beaker of boiling water. While the temperature of the copper is being raised to boiling point of water, a copper calorimeter is half filled with water. The initial temperature of the water is measured and recorded and the hot copper ball is lifted by the thread and transferred to the calorimeter when the water has reached boiling point. The calorimeter cover is put on, the mixture is well stirred and the final steady temperature read from the themometer. The copper ball is weighed either before or after the experiment. The result is tabulated as shown below.
Mass of copper ball - m (kg)
Temperature of boiling water - \(\theta\) (K)
Mass of copper calorimeter - \(m_{c}\) (kg)
Mass of calorimeter + water - \(m_{x}\) (kg)
Mass of water \((m_{x} - m_{c})\) - \(m_{w}\) (kg)
Specific heat capacity - C \((Jkg^{-1} K^{-1})\)
Initial temperature of water = \(\theta_{w}\) (K)
Final temperature of water = \(\theta_{f}\) (K)
Using Heat lost by copper ball = Heat gained by calorimeter + Heat gained by water
\(mc(\theta - \theta_{f}) = m_{c} c (\theta_{f} - \theta_{w}) + m_{w} c_{w} (\theta_{f} - \theta_{w})\)
\(c = \frac{m_{w} c_{w} (\theta_{f} - \theta_{w})}{m (\theta - \theta_{f}) - m_{c} (\theta_{f} - \theta_{w})}\)
Precautions: (i) The copper ball should be transferred quickly into the calorimeter without splashing. (ii) Just before transfer, the copper should be shaken slightly to remove adhering hot water.
(iii) Heat lost by copper ball = heat gained by copper calorimeter + Hoat gained by water.
\(m_{c} (\theta - \theta_{f}) = m c (\theta_{f} - \theta_{w}) + m_{w} c_{w} (\theta_{f} - \theta_{w})\)
\(20 \times 0.4 \times (200 - \theta_{f}) = 60 \times 0.4 \times (\theta_{f} - 30) + 50 \times 4.2 \times (\theta_{f} - 30)\)
\(8(200 - \theta_{f}) = 24(\theta_{f} - 30) + 210 (\theta_{f} - 30)\)
\(\theta_{f} = \frac{8620}{242} = 35.6K\)
View Discussion (0)WAEC 1994 THEORY.jpg)
In the diagram shown, which of the simple pendulum will resonate with P when set into oscillation?
- A. U
- B. T
- C. R and T
- D. Q and R
(a) In a school, the ratio of those who passed to those who failed in a History test is 4 : 1. If 7 students are selected at random from the school, find, correct to two decimal places, the probability that :
(i) at least 3 passed the test ; (ii) between 3 and 6 students failed the test.
(b) A fair die is thrown five times; find the probability of obtaining a six three times.
View Discussion (0)WAEC 2017 THEORYMonoculture is a term associated with
- A. livestock farming
- B. arable farming
- C. mixed farming
- D. plantation agriculture