Qualitative analysis of anions and cations

To a sample of A dilute sodium hydroxide solution was added dropwise then in excess. What two observations were made in order for Scientists to conclude that Fe²⁺ ions were present?

• observation when sodium hydroxide was added dropwise - A green ppt was formed Observation when sodium hydroxide was added in excess - The green precipitate dissolved to give a dark green solution

• observation when sodium hydroxide was added dropwise - A green ppt was formed Observation when sodium hydroxide was added in excess - The green precipitate remained

• observation when sodium hydroxide was added dropwise - A blue ppt was formed Observation when sodium hydroxide was added in excess - The blue precipitate dissolved to give a dark blue solution

• observation when sodium hydroxide was added dropwise - A White ppt was formed Observation when sodium hydroxide was added in excess - The white precipitate dissolved to give a colourless solution

• observation when sodium hydroxide was added dropwise - A White ppt was formed Observation when sodium hydroxide was added in excess - The white precipitate remained

To a sample of A dilute sodium hydroxide solution was added dropwise then in excess. What two observations were made in order for Scientists to conclude that Fe³⁺ions were present?

• observation when sodium hydroxide was added dropwise - A red-brown ppt was formed Observation when sodium hydroxide was added in excess - The green precipitate dissolved to give a red-brown solution

• observation when sodium hydroxide was added dropwise - A red-brown ppt was formed Observation when sodium hydroxide was added in excess - The red-brown precipitate remained

• observation when sodium hydroxide was added dropwise - A blue ppt was formed Observation when sodium hydroxide was added in excess - The blue precipitate dissolved to give a dark blue solution

• observation when sodium hydroxide was added dropwise - A White ppt was formed Observation when sodium hydroxide was added in excess - The white precipitate dissolved to give a colourless solution

• observation when sodium hydroxide was added dropwise - A White ppt was formed Observation when sodium hydroxide was added in excess - The white precipitate remained

To a sample of A dilute sodium hydroxide solution was added dropwise then in excess. What two observations were made in order for Scientists to conclude that Cu²⁺ions were present?

• observation when sodium hydroxide was added dropwise - A red-brown ppt was formed Observation when sodium hydroxide was added in excess - The green precipitate dissolved to give a red-brown solution

• observation when sodium hydroxide was added dropwise - A blue ppt was formed Observation when sodium hydroxide was added in excess - The blue precipitate remained

• observation when sodium hydroxide was added dropwise - A blue ppt was formed Observation when sodium hydroxide was added in excess - The blue precipitate dissolved to give a dark blue solution

• observation when sodium hydroxide was added dropwise - A White ppt was formed Observation when sodium hydroxide was added in excess - The white precipitate dissolved to give a colourless solution

• observation when sodium hydroxide was added dropwise - A White ppt was formed Observation when sodium hydroxide was added in excess - The white precipitate remained

To a sample of A dilute sodium aqueous ammonia solution was added dropwise then in excess. What two observations were made in order for Scientists to conclude that Cu²⁺ions were present?

• observation when aqueous ammonia was added dropwise - A red-brown ppt was formed Observation when aqueous ammonia was added in excess - The green precipitate dissolved to give a red-brown solution

• observation when aqueous ammonia was added dropwise - A blue ppt was formed Observation when aqueous ammonia was added in excess - The blue precipitate remained

• observation when aqueous ammonia was added dropwise - A blue ppt was formed Observation when aqueous ammonia was added in excess - The blue precipitate dissolved to give a dark blue solution

• observation when aqueous ammonia was added dropwise - A White ppt was formed Observation when aqueous ammonia was added in excess - The white precipitate dissolved to give a colourless solution

• observation when aqueous was added dropwise - A White ppt was formed Observation when aqueous ammonia was added in excess - The white precipitate remained

To a sample of A dilute sodium aqueous ammonia solution was added dropwise then in excess. What two observations were made in order for Scientists to conclude that Zn²⁺ions were present?

• observation when aqueous ammonia was added dropwise - A red-brown ppt was formed Observation when aqueous ammonia was added in excess - The green precipitate dissolved to give a red-brown solution

• observation when aqueous ammonia was added dropwise - A blue ppt was formed Observation when aqueous ammonia was added in excess - The blue precipitate remained

• observation when aqueous ammonia was added dropwise - A blue ppt was formed Observation when aqueous ammonia was added in excess - The blue precipitate dissolved to give a dark blue solution

• observation when aqueous ammonia was added dropwise - A White ppt was formed Observation when aqueous ammonia was added in excess - The white precipitate dissolved to give a colourless solution

• observation when aqueous was added dropwise - A White ppt was formed Observation when aqueous ammonia was added in excess - The white precipitate remained

To a sample of A dilute sodium hydroxide solution was added dropwise. What observation was made in order to conclude that if a cation was present it wasn't that of a metal?

• white precipitate formed

• no precipitate formed

• a yellow precipitate formed

• a blue precipitate formed

• a red-brown ppt formed

No precipitate was observed when dilute sodium hydroxide solution was added dropwise. What conclusion(s) could have been made?

• the cation present was Cu²⁺

• the cation present wasn't the cation of a metal

• the cation present was NH₄⁺

• the cation present was EITHER Al ³⁺, Pb²⁺, Zn²⁺ or Ca²⁺

• the cation present was Fe²⁺

A white precipitate was observed when dilute sodium hydroxide solution was added dropwise. What conclusion(s) could have been made?

• the cation present was Cu²⁺

• the cation present wasn't the cation of a metal

• the cation present was NH₄⁺

• the cation present was EITHER Al ³⁺, Pb²⁺, Zn²⁺ or Ca²⁺

• the cation present was Fe²⁺

No precipitate was observed when dilute sodium hydroxide solution was added dropwise. Then the resulting solution was heated and the gas evolved was tested. It was suspected that ammonium ions NH₄⁺ ions were present in the solution What further observations were made when the gas evolved was tested?

• The gas evolved turned blue litmus red and then bleached it

• The gas evolved turned blue litmus red

• the gas evolved made a filter paper soaked purple by potassium manganate solution was turned colourless

• The gas evolved turned red litmus blue

• The gas evolved turned Lime water ( Ca(OH)₂) solution into a cloudy white precipitate

A white precipitate was observed when dilute sodium hydroxide solution was added dropwise. Then to the same solution sodium hydroxide was added in excess. What conclusion(s) could have been made?

• the cation present was NOT Ca²⁺

• the cations responsible for the formation of the white precipitate were amphoteric since the precipitate was able able to react with excess sodium hydroxide and form something soluble

• then when the sodium hydroxide was added in excess and the white precipitate disappeared the cations present were EITHER Al ³⁺, Pb²⁺, Zn²⁺

• At first when the sodium hydroxide was added dropwise the cations present were EITHER Al ³⁺, Pb²⁺, Zn²⁺ or Ca²⁺

• the cation present was Fe²⁺