📌 How to Use
First read the questions carefully using the Read section. Use the Details button to understand concepts clearly. After completing reading, click Practice Quiz to test yourself.
📘 Study MCQs
Q1. you find a fuzzy green mould on a block of cheese. what should you do?
• throw the entire block away
• cut off at least one inch around the mould and use the rest
• scrape off the mould and eat the cheese
• put it in the freezer to kill the mould
Answer: cut off at least one inch around the mould and use the rest
with hard cheeses, mould threads cannot penetrate deeply. cutting a generous portion around and below the spot removes the contaminated part safely.
Q2. your idli/dosa batter has risen nicely overnight but you need to keep it for one more day. what is the best action?
• leave it on the kitchen counter
• stir it and keep it in the refrigerator
• add more water to it
• cook all of it immediately
Answer: stir it and keep it in the refrigerator
refrigeration slows down the fermentation process drastically. this prevents the batter from becoming too sour or over-fermented.
Q3. you are going on a picnic and want to carry homemade potato salad. how can you keep it safe to eat?
• pack it warm in a plastic box
• prepare it the night before, cool it, and pack it with an ice pack in an insulated bag
• add extra mayonnaise to preserve it
• leave it in the car trunk
Answer: prepare it the night before, cool it, and pack it with an ice pack in an insulated bag
potato salad is prone to bacterial growth. keeping it cold (below 5°c) with an ice pack prevents microbes from multiplying to dangerous levels.
Q4. a pot of cooked dal (lentils) was left out overnight. can you eat it?
• yes, just re-boil it well for 5-10 minutes
• no, it should be thrown away
• yes, if it smells okay
• no, but you can feed it to animals
Answer: no, it should be thrown away
cooked food left at room temperature for more than 2 hours (or 1 hour in hot weather) enters the “danger zone”. harmful bacteria can produce toxins that are not destroyed by reheating.
Q5. you bought too many bananas and they are ripening too fast. what can you do?
• put them all in the refrigerator
• separate them from each other and store in a cool, dry place
• place them in a sealed plastic bag
• put them in sunlight
Answer: separate them from each other and store in a cool, dry place
bananas release ethylene gas, which speeds ripening. separating them slows this process. the fridge skin will blacken, but the inside will be preserved longer.
Q6. your jar of pickles has a layer of white scum on top. what does it mean?
• it is extra salt, mix it in
• it is a harmless yeast or mould; remove it and the pickles are fine
• the pickles are spoiled and unsafe to eat
• it is crystallized sugar
Answer: it is a harmless yeast or mould; remove it and the pickles are fine
in fermented pickles, a white scum is often a harmless yeast or kahm yeast. skim it off. ensure the pickles remain submerged in brine to prevent it.
Q7. you want to keep cilantro (coriander leaves) fresh for a week. what method works best?
• leave it in the plastic bag from the store
• wash, dry thoroughly, place in an airtight container with a dry paper towel, and refrigerate
• put the bunch in a glass of water on the counter
• wrap it in a wet cloth
Answer: wash, dry thoroughly, place in an airtight container with a dry paper towel, and refrigerate
moisture causes wilting and decay. drying removes water that microbes need. the paper towel absorbs any condensation, keeping the leaves crisp.
Q8. you accidentally thawed a packet of frozen chicken on the counter for 5 hours. what should you do?
• refreeze it immediately
• cook it immediately and thoroughly
• it is still cold, so it’s safe to put back in the fridge
• smell it; if it’s okay, use it
Answer: cook it immediately and thoroughly
thawing at room temperature allows bacteria to multiply in the outer layers. cooking it immediately kills these bacteria. do not refreeze, as quality deteriorates.
Q9. you see a few sprouts on your potatoes. are they safe to eat?
• yes, just cut the sprouts off and use the potato
• no, the whole potato is poisonous now
• yes, the sprouts are nutritious
• no, but you can plant them
Answer: yes, just cut the sprouts off and use the potato
the sprouts and the green skin underneath contain solanine, which can be toxic. deeply cutting away the sprouted areas and any green parts makes the rest of the potato safe to eat.
Q10. your honey has crystallized and become solid. is it spoiled?
• yes, throw it away
• no, it is a natural process; gently warm the jar in warm water to liquefy it
• yes, crystals mean sugar has separated
• no, but you must freeze it now
Answer: no, it is a natural process; gently warm the jar in warm water to liquefy it
crystallization is natural for pure honey. it does not mean spoilage. warming it gently restores its liquid state without damaging its properties.
Q11. you are making yogurt, but the milk won’t set. what is a common reason?
• the milk was too hot when you added the starter
• the starter (old curd) was inactive or dead
• you used flavored yogurt as a starter
• all of the above
Answer: all of the above
too-hot milk kills the bacteria. an old or weak starter lacks live cultures. flavored yogurts may have additives that inhibit culture growth. any of these can prevent setting.
Q12. after a power cut, the fridge was off for 12 hours. how do you check if the food is safe?
• if the fridge door was shut, most items are safe if still cool to the touch
• taste everything
• if it smells okay, it’s fine
• throw away all dairy and meat immediately
Answer: if the fridge door was shut, most items are safe if still cool to the touch
a closed fridge keeps food cold for about 4-6 hours. after 12 hours, check the temperature. discard perishables (meat, dairy, cooked leftovers) if the temperature was above 5°c for over 2 hours.
Q13. you want to keep chapattis soft for tomorrow’s lunch. what should you do?
• stack them hot in a sealed plastic bag
• let them cool completely, then store in an airtight container
• keep them in the oven with the light on
• wrap them in a damp cloth
Answer: let them cool completely, then store in an airtight container
storing hot chapattis in a sealed bag creates steam and condensation, making them soggy and promoting microbial growth. cooling prevents this.
Q14. there is a bad smell coming from your kitchen sink drain. what is a likely cause and solution?
• pipes are broken, call a plumber
• food particles are decomposing in the drain; pour boiling water or a baking soda-vinegar mix down it
• ignore it, it will go away
• use strong chemical cleaners daily
Answer: food particles are decomposing in the drain; pour boiling water or a baking soda-vinegar mix down it
microbes decompose trapped food, causing foul smells. boiling water helps flush them out. baking soda and vinegar can help break down organic matter naturally.
Q15. your homemade jam has developed a few spots of mould on the surface. what should you do?
• scoop out the mould and use the rest
• the entire jar should be discarded
• add more sugar on top
• re-boil the jam and put it in a new jar
Answer: the entire jar should be discarded
mould in soft, high-moisture foods like jam can produce toxins that spread throughout the product, even if not visible. it is not safe to eat any part of it.
Q16. you need to store a large quantity of rice for months. what is the best method?
• keep it in the original sack in a corner
• transfer to airtight containers and store in a cool, dry place
• put it in the refrigerator
• leave the sack open for ventilation
Answer: transfer to airtight containers and store in a cool, dry place
airtight containers prevent moisture absorption (which leads to mould) and infestation by insects or rodents. a cool, dry place further inhibits microbial growth.
Q17. your water bottle, used for a day, has a slippery feel inside. why?
• it is the plastic degrading
• it is a biofilm of bacteria growing on the surface
• it is leftover soap
• it is just water
Answer: it is a biofilm of bacteria growing on the surface
bacteria from your mouth and the air can grow in the moist environment, forming a slimy layer called a biofilm. wash the bottle daily with hot, soapy water.
Q18. you want to quickly cool a large pot of hot soup before refrigerating it. how?
• put the whole hot pot in the fridge
• place the pot in a sink filled with ice water and stir occasionally
• leave it on the counter overnight
• add ice cubes to the soup
Answer: place the pot in a sink filled with ice water and stir occasionally
cooling food quickly prevents it from staying in the bacterial “danger zone” (5°c-60°c) for too long. an ice bath is the fastest safe method.
Q19. you see small black insects in your flour. what should you do?
• sift them out and use the flour
• throw away the entire bag of flour
• put the bag in the freezer to kill them
• mix in more flour to dilute them
Answer: throw away the entire bag of flour
the insects (weevils) and their larvae contaminate the flour with waste and microbes. it is best to discard it and thoroughly clean the storage area.
Q20. leftover canned food (like baked beans) is in an open can in the fridge. is this safe?
• yes, it’s still in the can
• no, transfer the contents to a covered container
• yes, if you use it within a day
• no, metal will poison the food
Answer: no, transfer the contents to a covered container
once opened, the tin lining can corrode and impart a metallic taste. more importantly, storing it covered prevents contamination from other fridge odors and microbes.
Q21. you are marinating meat for a barbecue. where should you keep it?
• on the kitchen counter for flavor to develop
• in the refrigerator
• in the sun to tenderize it
• in a sealed bag at room temperature
Answer: in the refrigerator
raw meat must be marinated in the refrigerator to prevent harmful bacteria like salmonella from multiplying rapidly at room temperature.
Q22. your homemade vinegar has tiny, worm-like strands floating in it. what are they?
• vinegar eels (nematodes), harmless but indicate non-sterile conditions
• maggots, throw it away
• plant fibers from the fruit, safe
• mould, discard it
Answer: vinegar eels (nematodes), harmless but indicate non-sterile conditions
vinegar eels are tiny worms that can live in unpasteurized vinegar. they are not harmful if ingested but are undesirable. it’s best to strain or discard that batch.
Q23. you want to reuse a glass jar for storing spices. what is a critical first step?
• wash it with soap and water
• sterilize it by boiling in water or running it through a dishwasher
• just wipe it clean
• use it as it is
Answer: sterilize it by boiling in water or running it through a dishwasher
sterilizing kills any microbes or residue from the previous contents that could spoil your spices or allow mould to grow.
Q24. you have a cut on your finger and need to knead dough. what should you do?
• knead as usual, the heat will kill germs
• wear a waterproof bandage or disposable glove
• avoid kneading
• put some turmeric on the cut and proceed
Answer: wear a waterproof bandage or disposable glove
this creates a barrier to prevent bacteria (like staphylococcus) from your skin from contaminating the food, which may not be cooked at a high enough temperature to kill them.
Q25. you are storing cooked rice for later. how long can it safely stay at room temperature?
• up to 6 hours
• up to 2 hours
• up to 8 hours
• overnight is fine
Answer: up to 2 hours
cooked rice can contain spores of bacillus cereus, which can germinate and produce toxins at room temperature. refrigerate it within 2 hours of cooking.
Q26. your fridge has a persistent musty smell. what is a common cause and fix?
• the motor is failing
• spoiled food is hidden somewhere; remove all items, clean shelves with baking soda solution
• it’s normal for old fridges
• spray air freshener inside
Answer: spoiled food is hidden somewhere; remove all items, clean shelves with baking soda solution
the smell is often from mould or bacteria growing on spilled food. a thorough clean with baking soda (which neutralizes odors) removes the source.
Q27. you are making lemonade for a party. how can you prevent the cut lemons from making it bitter if prepared ahead?
• squeeze the lemons and discard the peels before refrigerating the juice
• leave the lemon slices in the pitcher
• add the lemon slices just before serving
• use warm water
Answer: squeeze the lemons and discard the peels before refrigerating the juice
the white pith and peel contain bitter compounds (limonin) that seep into the juice over time. juicing and straining removes this risk.
Q28. you bought paneer (cottage cheese). how should you store it to keep it fresh?
• keep it in the packet with water
• drain the water, put the paneer in an airtight container with fresh water, and refrigerate, changing water daily
• leave it on the counter in a bowl
• freeze it immediately
Answer: drain the water, put the paneer in an airtight container with fresh water, and refrigerate, changing water daily
storing paneer submerged in fresh, cold water keeps it moist and prevents it from drying out or absorbing fridge odors. changing water prevents bacterial growth in the water.
Q29. you want to keep your kitchen sponge from smelling bad. what helps?
• rinse it and leave it on the sink
• rinse, wring out, and let it dry completely between uses
• keep it in a sealed bag
• microwave it daily when damp for 1 minute
Answer: rinse, wring out, and let it dry completely between uses
a damp sponge is a breeding ground for bacteria and mould, causing odours. letting it dry thoroughly inhibits microbial growth.
Q30. you are unsure if a carton of milk is still good, but the expiry date is today. how can you check?
• taste a small sip
• smell it; sour milk has a distinct, unpleasant sour odour
• see if it’s curdled when poured into a glass
• both b and c are good checks
Answer: both b and c are good checks
smell and visual inspection are reliable. sour smell or obvious lumps/curdling indicate spoilage by lactic acid bacteria, even if the date is recent.