Question

Answer the following questions in one or two sentences
i) What is the percentage of gold present in 'Hallmark' gold?
ii) What is the meaning of 'chalcogens'?
iii) What are the metals used in the manufacture of science equipment?
iv) Name the metal present in chlorophyll which is used in photosynthesis.
v) When iron is exposed to moist air, a reddish brown substance is deposited on it.
What is it? Give its composition.

Answer 1

$\left(I\right)$ Hallmark is the quality certification to gold certifying the purity of the metal. it is $916$ i.e $91.6$ gm gold in $100$ gm of alloy

$\left(II\right)$ Chalcogens $-$ are the elements of group 16 -oxygen family oxygen, sulfur, selenium, Tellurium, polonium. All found in copper ores hence chalcogens.

$\left(III\right)$ Aluminium, brass, bronze, gold, copper, steel titanium.

$\left(IV\right)$ magnesium.

$\left(V\right)$ It is rust.

Composition : ${Fe}_2{O}_3.x{H}_{2}O$