Which of the following is precancerous lesion -
Pachydermia of larynx
Laryngitis sicca
Keratosis of larynx
Scleroma larynx
Lichen planus has no malignant potential.

Papilloma– “The malignant transformation from benign non keratining squamous papilloma to squamous cell carcinoma can occur in children, but is rarely seen” 
Leukoplakia is a white patch, in which there is epithelial hyperplasia along with atypical cells. It is a premalignant condition. Another name for leukoplakia is hyperkeratosis dyskeratosis
Smoking is a predisposing factor, not a premalignant condition. y In some cases of chronic laryngitis, the laryngeal mucosa becomes dysplastic particularly over true vocal folds and is a premalignant condition.
Chronic inflammatory conditions of larynx like chronic laryngitis may develop into malignancy.

Keratosis of larynx/leukoplakia:- 
It is epithelial hyperplasia of the upper surface of one or both vocal cords.

Appears as a white plaque or warty growth on cord without affecting its mobility
Regarded as a precarcerous condition as Ca in situ develops frequently
T/t = stripping of cords