What volume of coppr ( density 8.96g/cm3)would be needed to balance a 2.28 cm3sample of lead (density 11.4g/cm30 on a two-pan laboratory balance

2.9 cm³

Step-by-step explanation:

Note: For the copper and the lead to balance, they must have thesame mass.

Applying,

D' = m'/V Equation 1

Where D' = density of the lead, m' = mass of the lead, V = Volume of the lead.

make m' the subject of the equation

m' = D'V Equation 2

From the question,

Given: D' = 11.4 g/cm³, V = 2.28 cm³

Substitute these values into equation 2

m' = (11.4×2.28)

m' = 25.992 g

Similarly,

for copper,

D = m/V Equation 3

Where D = density of  copper, m = mass of copper, V = volume of copper.

make V the subject of the equation

V = m/D Equation 4

where, m = m' = 25.992 g

Given: D = 8.96 g/cm³

Substitute these values into equation 4

V = 25.992/8.96

V = 2.9 cm³

step-by-step explanation:

this is not a question

percentage - 25%

probability - 0.25

we know,

total amount of students in class = 20

total boys = 10

total girls = 10

no of girls who wear glasses = 10/2 = 5

probability of choosing a girl with glasses is =

number of girls wearing glasses/total number of students in the class = 5/20

thus, percentage of selecting a girl wearing glasses will be

= 5/20 × 100

= 5 × 5

25%

therefore,

probability will be 0.25

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