The more accurate statement regarding the stability of a double-bonded carbon is: "The more H's attached to the carbon that is double-bonded, the more stable the compound."
In organic chemistry, stability of double-bonded carbons (alkenes) can be influenced by the degree of substitution of the double bond. Alkenes with more hydrogen atoms attached (i.e., more α-hydrogens) generally exhibit greater stability due to hyperconjugation and reduced steric strain. Conversely, while more carbons can increase substitution (and sometimes stability depending on other factors), the presence of hydrogen atoms directly contributes to the overall stability of the compound.
For example, terminal alkenes (with fewer R groups and more H's) are typically less stable than internal alkenes (which are more substituted and have a higher number of carbon atoms attached). Therefore, stability typically increases with the number of substituents (more carbon groups), but the initial statement regarding hydrogen is a more common consideration in terms of direct stability.
In summary, while both statements touch on aspects of stability, the first statement regarding hydrogen attachment more directly correlates with the typical analysis of alkene stability.