Questions asked by shevon85

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• Draw a similar diagram to represent the structure of an atom of 37Cl and suggest an explanation for each of the following observations? a. Atoms of 35Cl and 37Cl have the same chemical properties. b. Atoms of 35Cl differ from those of 37Cl. c. 1 mole of c
  
• Name one element whose atoms are converted into ions with three positive charges. Write the ionic equation for this element?
  
• 1 mole of chlorine molecule has a mass 71 grams? Explain please.
  
• Explain, giving reasons for your answer, why Calcium is more reactive than Magnesium but less reactive than Sodium?
  
• Calculate the tensile stress in a nylon fishing line of diameter 0.36 mm which a fish is pulling with a force of 20 N?
  
• Find the minimum diameter of an alloy cable, tensile stress75 MPa (75,000,000 Pa), needed to support a Force of 15 kN (15,000 N)?
  
• The pressure of a gas at 35.60C is 114.3kPa. What is the pressure when the temperature drops to 17.3 0C? Assume constant volume?
  
• What is the pressure of a gas if you compressed the gas from its original 500 mL at 3.4 torr to a volume of 302 mL?
  
• A 21.5L sample of gas at 107kPa has a temperature of 27.20C. What is the pressure of the gas if it is transferred to a 32.6L container at 44.10C?
  
• How much heat is needed to raise the temperature by 10 0C of 5 kg of a substance of specific heat capacity 300 J/ (kg 0C)?
  
• How much heat is needed to raise the temperature by 10 0C of 5 kg of a substance of specific heat capacity 300 J/ (kg 0C)?
  
• Some small aluminium rivets of total mass 170 g and at 100 oC are emptied into a hole in a large block of ice at 0 oC. i. What will be the final temperature of the rivets? ii. How much ice will melt?
  
• What is the current in a circuit if the charge passing each point is 10 C in 2 s, 20 C in 40 s, 240 C in 2 minutes?
  
• The p.d. across a lamp is 12 V. How many joules of electrical energy are changed into light and heat when i. a charge of 1 C passes through it, ii. a charge of 5 C passes through it, iii. a current of 2 A flows in it for 10 s?
  
• If the current in a floodlamp is 5 A, what charge passes in 1 s, ii. 10 s, iii. 5 minutes?
  
• How much heat is needed to change 4 g of water at 100 oC to steam at 100 oC?
  
• Find the heat given out when 10 g of steam at 100 oC condenses and cools to water at 50 oC?
  
• An aluminium can of mass 100 g contains 200 g of water. Both, initially at 15 oC, are placed in a freezer at 5.0 oC. Calculate the quantity of heat that has to be removed from the water and the can for their temperatures to fall to -5.0 oC.?
  
• What is the resistance of a lamp when a voltage of 12 V across it causes a current of 4 A?
  
• Calculate the p.d. across a 10 Ω resistor carrying a current of 2 A.?
  
• The p.d. across a 3 Ω resistor is 6 V. What is the current flowing (in ampere)? A. 0.5 B. 1 C. 2 D. 6 E. 8?