Is carbon a gas at stp ?

Nope,

Carbon exists in various allotropes (different forms of the element in the same state): 

1. Graphite

2. Diamond

3. Buckminsterfullerene

4. Graphene

5. Various nanomaterial

All are solid at STP

Depends on what it's bonded with:

Carbon bonded with Carbon: black solid

Carbon with O₂: gas

C with O₁: deadly gas

C with Chlorine: cleaning fluid liquid

C with H₄: methane gas

C with Hydrogen and Oxygen: Sugar, alcohol, or gasoline

In one word NO!!!! 

At stp Carbon is a black solid.  (Soot if you like).

It has a sublimation point of 3915 K ( 3642 degrees C) where it changes from solid to gas. 

However carbon can exhibit three allotropes, all of which are solids at stp. 

they are :- Graphite (the black solid) , Diamond ( the shiny gemstone) and the Buckminster Fullerene(Footballene) (C60) (Only discovered in the last 40 years).  

NB ; Carbon Dioxide (CO2) is a gas at stp.  

NNB Don NOT confuse 'Carbon' and Carbon dioxide', they are two different substances.  

Ha ha, you'd have a hard time writing with a pencil if the "lead" (which is mostly carbon) were trying to send its molecules all over the room.  The melting point of solid carbon is 3367C, and the boiling point, where it becomes a gas, is over 4800C.  

Nope, at standard pressure and temperature, graphite, caramel, diamond and grapheen are solids