# Mass - 9th grade (14y) - practice problems

#### Number of problems found: 224

- Nitric acid

We want to prepare 200 g of 30% nitric acid. We have enough 12% and 60% of this acid. How many of which will we need? - Bronze

Bronze has 80% copper and 20% tin. How much copper will we need to produce bronze if we have 39kg of tin? - Mushrooms

The ratio of dry matter and water is 1: 9 for most mushrooms. Dry matter consists of carbohydrates, proteins, minerals, fat and water in a ratio of 50: 30: 8: 3: 9. How many kg of fresh mushrooms need to be processed into a 10 kg package of dried mushroom - KOH

How many g of 20% KOH solution do we need to mix with 500 g of 30% KOH solution to obtain a 25% KOH solution? - Ice to boiling water

Calculate the heat needed to convert 5kg of ice with a temperature of -5°C to water with a temperature of 100°C. c (water) = 4200 J. Kg-1. kg-1, c (ice) = 2100 J. Kg-1. kg-1. the mass group heat of solidification of water is l = 334kJ/kg. Calculate the he - Salt solution

Calculate the weight of a 50% salt solution that we prepare from 120 g of salt. - Beef taxation

How much should the price of 2.5 kg of beef change, which in December cost € 5.71 per 1 kg if VAT changed from 20% to 10%. how much will 2.5kg cost from January? - Shen's

Shen's chocolate bar is 54% cocoa. If the weight of the chocolate bar is 54 grams, how many grams of cocoa does it contain? Round your answer to the nearest tenth. - Dynamometer

What is the volume of a body that stretches a dynamometer in air, on which it is suspended by a force of 2.5 N, and if it is immersed in alcohol with a density of 800 kg/m ^ 3, does it tension the dynamometer with a force of 1.3 N? - Above water surface

If we remove the stone from the water, we apply a force of 120N. How much force will we have to exert if we move the stone above the water surface? The density of the stone is 5000 kg/m ^ 3. - Bottle, cup and jug

The bottle and the cup have the same weight as the jug. The bottle has the same weight as the cup and plate. Two jugs have the same weight as three plates. What is the weight of the bottle, if the weight of the cup is 100g. - There

There is 5 l of water with a temperature of 20°C in the bucket. We add 3 liters of hot water. The resulting temperature will be 30°C. What was the temperature of the hot water? - Feed to hay

How many tons of water do we have to dehydrate from 8 tons of feed, if the original moisture is 54 percent, to get hay with a moisture content of 15 percent? Round to two decimal places. - School model

The beech school model of a regular quadrilateral pyramid has a base 20 cm long and 24 cm high. Calculate a) the surface of the pyramid in square decimeters, b) the mass of the pyramid in kilograms if the density of the beech is ρ = 0,8 g/cm ^ 3 - Latent heat

How much heat is needed to take from 100 g of water at 20°C to cool to ice at -18°C? Mass heat capacity c (ice) = 21kJ/kg / °C; c (water) = 4.19 KJ/kg / °C and the mass group heat of solidification of water is l = 334kJ/kg - Heat transfer

We placed a lead object weighing 0.4 kg and 250°C in 0.4 L water. What was the initial temperature of water t2 if the object's temperature and the water after reaching equilibrium was 35°C? We assume that the heat exchange occurred only between the lead o - A semi-circular

A semi-circular fishbowl is filled with water and has a diameter of 10 feet. What is the total weigh of water to the nearest pound in the tank, if water weighs 62.5 pounds per cubic foot? - Two boys

Two boys weighing 60kg and 90kg move on roller skates and are attracted to each other by a rope. One boy exerts a force of 15N. What force does the other boy exert? What accelerations will the boys gain? Do not consider friction or air resistance. - The square

The square oak board (with density ρ = 700 kg/m^{3}) has a side length of 50 cm and a thickness of 30 mm. 4 holes with a diameter of 40 mm are drilled into the board. What is the weight of the board? - The aluminum

The aluminum object with a weight of 0.80 kg and a temperature of 250°C was placed in the water with a weight of 1.6 kg and a temperature of 23°C. What is the system temperature after reaching equilibrium? We assume that the heat exchange occurred only be

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Mass - practice problems. Examples for 9th grade.