Alkanes and alkenes differ in that alkene molecules contain at least one:
A. oxygen atom
B. double bond
C. triple bond
D. chlorine atom

Double bond

Explanation:

an alkene is a unsaturated hydrocarbon which means that it contain at least one double bond

The answer to your question is B. double bond.

Explanation:

Both alkanes and alkenes are hydrocarbons composed by carbon and hydrogen.

The different between these compounds is that alkanes have only single bonds are are represented as:         H    H

                                                            |     |

                                                     H - C - C - H

                                                            |      |

                                                           H    H

Alkenes have at least one double bound in their structure and are represented as

                                                   H - C = C - H

                                                          |      |

                                                          H    H

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.