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1. 

Brass gets discoloured in air because of the presence of which of the following gases in air?
A. Oxygen
B. हाइड्रोजन सल्फ़ाइड
C. कार्बन डाइआक्साइड
D. नाइट्रोजन
2. 

Which of the following is a non metal that remains liquid at room temperature?
A. Phosphorous
B. ब्रोमिन
C. क्लोरीन
D. हीलियम
3. 

Which of the following is used in pencils?
A. Graphite
B.

सिलिकन
C.

लकड़ी का कोयला
D.

फ़ास्फ़रोस
4. 

Chlorophyll is a naturally occurring chelate compound in which central metal is
A. copper
B.

मैग्नीशियम
C.

लोहा
D.

कैल्शियम
5. 

Which of the following metals forms an amalgam with other metals?
A. Tin
B.

पारा
C.

लीड
D.

जस्ता