The reaction between metallic silver and aqueous NaCN forming a soluble complex occurs in the presence of :
nitrogen
oxygen
helium
chlorine
Lanthanides and actinides are also called :
short periods
inner-transition elements
long periods
main transition elements
Assertion : Fe3+ can be used for coagulation of As2S3 sol.
Reason : Fe3+ reacts with As2S3 to give Fe2S3.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
C.
If assertion is true but reason is false.
Fe3+ is positively charged whereas As2S3 is negatively charged sol. Their charges are neutralised on mixing hence, mutual precipitation (coagulation) occurs.