Three students measure the mass of the same object. We can say with certainty th

Question

Three students measure the mass of the same object. We can say with certainty that these measurements are (A) precise (B) accurate (C) both accurate and precise (D) Neither accurate nor precise Which is a precipitation reactions? (A) 2Cr(s) + 6HNO_3 (aq) rightarrow Cr(NO_3)_3 (aq) + 3H_2(g) (B) H_3PO_4(aq) + 3KOH(aq) rightarrow K_3PO_4(aq) + 3H_2O(l) (C) NaHCO_3(aq) + HCl(aq) rightarrow NaCl(aq) + CO_2(g) + H O(l) (D) 3Ba(NO_3)_2 (aq) + 2 Na_3PO_4(aq) rightarrow 2 Ba (PO_4)_2 (s) + 6 NaNO (aq) Which could be both an empirical formula and a molecular formula? (A) CH_3COOH (B) HNF_2 (C) Hg_2Cl_2 (D) N_2O_4 If 1.958 g of solid NaNO_3 is dissolved in enough water to make 500.0 mL of solution, what is the molarity of the solution? (A) 4.607 times 10 M (B) 4.607 times 10^-2 M (C) 3.916 times 10 M (D) 2.304 times 10^-2 M How many unpaired electrons does a cobalt (Co) atom have in the ground state? (A) 7 (B) 5 (C) 3 (D) 1 What is the percent by mass of potassium in K_2HPO_4? (A) 44.9% (B) 25.9% (C) 22.4% (D) 17.8% Which process is endothermic: A) neutralization of HCl with NaOH. (B) Combustion of magnesium. (C) Condensation of water vapor. (D) melting of ice. How many milliliters of 3.5 M NaCl must be diluted to prepare 250 mL of 0.45 M NaCl? (A) 1.9 times 10 mL (B) 1.6 times 10 mL (C) 32 mL (D) 0.031 mL When a 25.0 g sample of a metal 98.0 degree C is placed in 40.0 g of water at 18.0 degree C, the final temperature of the system is 25.0 degree C, what is the specific heat of the metal (A) 27 J/g degree C (B) 1.2 J/g degree C (C) 0.64 J/g degree C (D) 0.12 J/g degree C What is the electron configuration of Fe: (A) [Ar] 4s 3d (B) [Ar] 4s 3d (C) [Ar] 4s 3d (D) [Ar] 3d How many moles of carbon are there in 852 g of calcium oxalate, CaC_2O (molar mass, 128.10 g/mol)? (A) 71.0 (B) 13.3 (C) 6.65 (D) 3.33 What is the geometry of the NO^-_2 anion? (A) linear (B) trigonal pyramidal (C) trigonal planar (D) angular or bent What is the hybridization of central atom carbon in COCl_2? (A) sp^3 d (B) sp^3 (C) sp^2 (D) sp

Explanation / Answer

58) since u dont know that accurate answer to the solution, the answers given by students may or may not be correct. But here all the answers are very close. So, this values has more PRECISION.

59) Fformation of solid in the reaction is said to be precipitation reaction. So in option (D) solid is forming .It is correct answer

60) HNF2 cannot be divided with any other number where as other can be divided with 2. So, answer is HNF2

61) Molarity = moles / volume = (mass/ molar mass)/ volume in L = ( 1.958 g / 85 g/mol ) / 0.5 L = 0.046 M

62) Co is Ar 3d7 4s2  , in 3d orbital 4 electrons are paired and remaining 3 are unpaired.

63) K mass in K2HPO4 = 2 x 39.0 = 78

Molar mass of K2HPO4 = 174.2 g/mol

so mass% = ( 78 g /174.2) x100 == 44.9%

64)

acid + base = salt+ water + heat -----> exothermic

combustion is exothermic

water vapor turns to water and give heat . So, exothermic.

Ice needs some heat energy to convert to water. So endothermic process

pls post remaining questions separately.

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