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The metallic constituents of hard water are

A. Calcium, magnesium and iron

B. Magnesium, Calcium and tin

C. Magnesium, tin and iron

D. Iron, tin and calcium

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  1. The recent atomic weight scale is based on
  2. Rust is
  3. Water has maximum density at
  4. Which of the following characters is not shown by hydrogen
  5. One fathom is equal to
  6. What is the unit for measuring the pitch or frequency of sound ?
  7. Which of the following parts of the sun is easily visible only during a total solar eclipse?
  8. The marine animal called dugong which is vulnerable to extinction is a/an
  9. The hardest substance available on earth is
  10. Permanent hardness of water can be removed by adding
  11. The most important ore of Aluminium is
  12. The formula of Plaster of Paris is
  13. Lightening cause rainfall because
  14. Quartz crystals normally used in quartz clocks etc. is chemically
  15. When a gas is turned into a liquid, the process is called
  16. Apparatus invented by Archimedes is :
  17. Old-written material, which cannot be read easily can be read by
  18. Glass is made from the mixture of
  19. The metal used in storage batteries
  20. According to Daltons atomic theory the smallest particle which can exist independently is
  21. Carbon tetrachloride fire extinguisher should not be used in closed room because it produces poisonous…
  22. The solar eclipse occurs when
  23. The intencity of Earthquakes is measured on
  24. In a certain electronic circuit the output is positive if input 1 is positive and input 2 is zero. If…
  25. Which of the following is the lightest metal ?
  26. Brass gets discoloured in air due to the presence of which gas in air
  27. In an atomic nucleus, neutrons and protons are held together by
  28. Which of the following elements is non-radioactive?
  29. The colour of Emerald is
  30. The fastest acting enzyme in the biological kingdom is