Percentages + density - practice problems
Number of problems found: 23
- Water percent
A 15 g sample of the substance contains 70% water. After drying, the substance reduced its weight to 9 g. What percentage of water is now in the sample? - Density 3701
4.8g / l a) what is mg / l b) What is per mille if the density of alcohol is 80% of the density of blood (water)? - Alcohol
6l 48% alcohol, how much must we add 52% alcohol to give 50% alcohol? - Wood
Wood contains 12% water. One m³ of wood weighs 650 kg. How many liters of water does it contain? - Alcohol
How much 56% alcohol do we need to pour into 22 liters 78% alcohol to get p3% alcohol? How much 76% alcohol do we get? - Semi-skimmed 82206
The dairy produces semi-skimmed milk (with 1.5% fat content) by skimming part of the fat from full-fat milk (with 4% fat content). 1 ton of semi-skimmed milk is produced from how many kilograms of fat milk? - Spirit
From 55% and 80% spirit, we would like to produce 0.2 kg of 60% spirit. How many of them must we use in a solution? - Sea water
Seawater contains about 5% salt. How many dm³ of distilled water must we pour into 39 dm³ of seawater to get water with 1.6% salt? - Sea water
Mixing 62 kg of seawater with 84 kg rainwater is created water containing 3.1% salt. How much percent of seawater contains salt? - Fertilized 80437
Nitric lime contains an average of 19% nitrogen and 55% calcium oxide. How many grams of nitrogen per 1 m² if we bought a 25 kg package and thereby evenly fertilized a garden of 12 a? - Concentration 27551
We need a 4% solution of H2O2 (hydrogen peroxide) for the disinfection solution. We only have a 40% solution available. How much water do we need to add to 100ml of the original solution to obtain the desired concentration? - Natural fertilizer
The gardener fertilized the rectangular garden measuring 120m and 60m with 16kg of natural fertilizer. Natural fertilizer contains 45% organic matter. How much organic matter falls on 1 m² of the garden? - Calculate 33911
Calculate the volume of 50% KI solution and the volume of 20% KI solution needed to prepare 180g of 30% KI solution. The solution densities are known: ρ50% = 1.54575 g / cm3, ρ20% = 1.16597 g / cm³. - Approximately 80443
The 94 m² flower bed is to be planted with begonias. An area of 2 dm² is needed for one seedling. How many grams of seeds should be sown if 1 g of seeds contains approximately 5000 seeds? Losses when growing seedlings are usually 30%. - Rectangular 7215
The rectangular rink with dimensions of 50 m and 25 m should be covered with a layer of ice 4 cm high. How many liters of water are needed to make ice if the ice volume is 10% greater than the volume of water? - Ice and water
We want to cover a rectangular rink with dimensions of 55 m and 25 m with a 4cm thick layer of ice. How many liters of water do we need if freezing water increases its volume by 10%? - Prescribed 4579
The racing ball for men has a prescribed weight of 7250g. It is made of iron. How does its diameter change if we make it from lead? The density of iron is 7.8 g / cm cubic, and the density of lead is 11.3 t / m cubic. - Icerink
A rectangular rink with 68.7 m and 561 dm dimensions must be covered with a layer of ice 4.2 cm thick. How many liters of water is necessary for ice formation when the ice volume is 9.7% greater than the volume of water? - Vinegar 2
How many percentages of vinegar solution will we get if we mix 3.5 liters of 5.8% and 5 liters of 7.6% vinegar? - Difference 69354
An airplane flies at a speed of 920 km/h at an altitude of 11 km above the surface of the Earth, where the air density is p = 0.36 kg/m³. Determine the pressure difference above and below the plane's wing if the top of the plane is 10% longer than the bot
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