Doubtly
@Doubtly · Joined Feb 2021
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- A boat travels 16 km upstream and 24 km downstream in 6 hours. speed of the boat in still water is 8 km/hr. and speed of water current is 4 km/hr. 1
- P. Perform each of the following calculations. Round off your answers to two digits Refer below image for detailed solution 2
- Q. Perform each of the following calculations. Round off your answers to three digits. Solution:: 5.02×10¹⁰ , 2
- R. Perform the following operations : a. 3.971 × 107 + 1.98 × 104 ; b. 1.05 × 10-4 - 9.7 × 10-5; c. 4.11 × 10-3 + 8.1×10-4; d. 2.12 × 106 - 3.5 × 105 A) 3.971 × 10⁷ + 1.98 × 10⁴ = 3.971 × 10⁷ + 0.00198 × 10⁷ = (3.971 + 0.00198) × 10⁷ = 3.97298 × 10⁷ B) 1.05 × 10⁻⁴ − 9.7 × 10⁻⁵ = 10.5 × 10⁻... 2
- A 1.000 mL sample of acetone, a common solvent used as a paint remover, was placed in a small bottle whose mass was known to be 38.0015 g. Precision: Measurement Mass of acetone observed (g) 1 38.7798-38.0015=0.7783 2 38.7795-38.0015=0.7780 3 38.7801-38.0015=0.7786 Mean= 0.7783... 2
- T. Your laboratory partner was given the task of measuring the length of a box (approx 5 in) as accurately as possible The metre stick is graduated in millimetres i.e. 1 mm to 1000 mm, and 1 mm = 0.1 cm. Therefore, if length is measured in centimetres, the le... 1
- 3. Give one example of each A. homogeneous mixture B. heterogeneous mixture C. element D. compound A. homogeneous mixture Ans) the molecules of constituent solute and solvent are uniformly mixed throughout its bulk. For example : Sugar and... 1
- A. What is the ratio of molecules in 1 mole of NH3 and 1 mole of HNO3 . Correct answer is 1:1 one mole of any substance,compound , or elements contain particles equal to avagadro's number i.e. 6.022 × 10²³ theref... 1
- B. Calculate number of moles of hydrogen in 0.448 litre of hydrogen gas at STP Given : volume of hydrogen at STP =0.448 L To find : number of moles of hydrogen Formula : number of moles of a gas = Volumespace of space a... 1
- C. The mass of an atom of hydrogen is 1.008 u. What is the mass of 18 atoms of hydrogen. Given : mass of hydrogen = 1.008 u To find : mass of 18 atoms of hydrogen Solution : mass of 18 atoms of hydrogen = 18 × mass of hydrogen =... 1
- D. Calculate the number of atom in each of the following (Given : Atomic mass of I = 127 u). Given : atomic mass of I=127 u A. 254 u of iodine (I) Formula : number of atoms = given space atomic space mass space of space elementover a... 1
- O. What is volume of carbon dioxide, CO2 occupying by i. 5 moles and i. 5 moles of CO_(2 )gas measured at STP. Solution :: molar volume of gas at STP is 22.4 dm³ mol⁻¹ (n)Number of moles of gas = Volumespace o... 1
- P. Calculate the mass of potassium chlorate required to liberate 6.72 dm3 of oxygen at STP beginmatrix 2KClO₃ &→ 2KCl&+3O₂\\ 2moles & & 3 moles endmatrix 2 moles of KClO₃ = 2× 122.5=245g 3 moles of O₂ =3× 22.4=67.2 dm³ hence , 245... 1
- Q. Calculate the number of atoms of hydrogen present in 5.6 g of urea, (NH2 )2 CO No of atoms of H= 2.24× 10²³ , N= 1.124× 10²³ , C= 0.562×10²³, O= 0.562× 10²³ 1
- R. Calculate the mass of sulfur dioxide produced by burning 16 g of sulfur in excess of oxygen in contact process. Answer is 32 grams 1
- Explain The need of the term average atomic mass i. Several naturally occurring elements exist as a mixture of two or more isotopes. ii. Isotopes have different atomic masses. iii. The atom... 1
- Explain Molar mass. The mass of one mole of a substance (element/compound) in grams is called its molar mass. The molar mass of any element in grams is numerica... 1
- Explain Mole concept. Even a small amount of any substance contains very large number of atoms or molecules. Therefore, a quantitative adjective 'mole' is used to... 1