Limonene is an oil from oranges and lemons. Click on all the carbon atoms its structures that have a trigonal planar molecular geometry.

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Explanation:

Limonene is an oil from oranges and lemons. Its structure has been shown in the image attached to this answer.

There are two different groups of carbon atoms in limonene. One group of carbon atoms are sp2 hybridized while the other group are sp3 hybridized. The group of carbon atoms that are sp2 hybridized have a trigonal planar geometry and have been accurately labeled in the image attached while the carbon atoms that are sp3 hybridized were also labelled and have a tetrahedral geometry.

Hence in limonene, there are trigonal planar and tetrahedral carbon atoms.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.