The gas used in artificial ripening of green fruits is

• ethane
  
  

• hydrogen
  
  

• acetylene
  
  

• nitrogen

Which of the following properties of water can be used to explain the spherical shape of rain droplets?

• Surface tension
  
  

• Critical phenomenon
  
  

• Viscosity
  
  

• Pressure.

Which of the following is a greenhouse gas?

• Nitrogen
  
  

• Carbon dioxide
  
  

• Argon
  
  

• Oxygen

Which one of the following metals is not a mineral?

• Bauxite
  
  

• Gypsum
  
  

• Hematite
  
  

• Limonite

Which one of the following non-metals is liquid?

• Iodine
  
  

• Sulphur
  
  

• Bromine
  
  

• Phosphorus

Which scientist discovered the radioactive element radium?

• Albert Einstein
  
  

• Benjamin Franklin
  
  

• Isaac Newton
  
  

• Marie Curie

What is the reason of 'stone-cancer'?

• Global warming
  
  

• Radioactivity
  
  

• Acid rain
  
  

• Bacterial activity

The percentage of nitrogen gas in the air is

• 78
  
  

• 21.5
  
  

• 40
  
  

• 3

Ozone is

• an allotrope of oxygen
  
  

• an isomer of oxygen
  
  

• a compound of oxygen
  
  

• an isotope of oxygen

Which one of the following materials is ferromagnetic?

• Nickel
  
  

• Wood
  
  

• Gold
  
  

• Manganese