വിഡ്ഢികളുടെ സ്വർണം എന്നറിയപ്പെടുന്നത് ഏത് ?

Which one of the following minerals contain mostly silica?

The atomic theory of matter was first proposed by

Which one of the following is not true for diamond?

Which one of the following statements is not correct?

Which of the following is not a gaseous air pollutant?