281. The setting time of irreversible hydrocolloids can be decreased by_____________?

A. Raising the temperature of water used for maxing
B. Using excess water for maxing
C. Lowering the temperature of water used for mixing
D. None of the above

282. Rubber base impressions are poured immediately as they_______________?

A. Continue to polymerize
B. Become elastic
C. Show imbibition and syneresis
D. Show gelation

283. The most mucostatic impression material is_______________?

A. Thin mix of plaster of paris
B. Zinc oxide eugenol impression paste
C. Free flowing wax
D. Reversible hydrocolloids

284. Palatal secretions affect the setting of all the impression materials except_______________?

A. Silicone
B. Agar-agar
C. Impression paste
D. Impression plaster

285. Lenolin is added is ZOE paste to______________?

A. Decrease flow
B. Increase flow
C. Accelerate reaction
D. Decrease irritation due to eugenol

286. Agar is prepared from_______________________?

A. Bullock heart
B. Chemicals
C. Sea weed
D. Chick cells

287. Perforated impression tray are used for_______________?

A. Alginate
B. Zinc oxide-eugenol
C. Agar-agar
D. Impression compound

288. During setting of alginate impression materials________________?

A. Trisodium phosphate reacts with sodium alginate
B. Trisodium phosphate reacts with calcium sulphate
C. Colloidal changes to sol
D. Material in contact with soft tissues sets last

289. The best way to remove a hydrocolloid impression from the patient’s mouth is____________?

A. Slight rocking of the impression to disengage it from the undercut
B. Wetting the periphery of the impression with moist cotton to break the peripheral seal
C. Sudden jerking of the impression to prevent tearing
D. Supporting the impression along with the tray to prevent disengaging of the tray alone

290. K2SO4 in agar-agar is for_______________?

A. Accelerating the setting stage of gypsum
B. Increase strength
C. Give dimensional stability
D. None of the above

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