<prompt> In antacid preparation aluminum hydroxide is added with magnesium salt because -Magnesium caused constipationTo counteracts constipating effect of aluminum hydroxideTo counteract the diarrhea action of aluminumAluminum salt causes diarrhea  <response>: Ans is b i.e., To counteracts constipating effect of aluminum hydroxide o Magnesium salts are laxative and aluminium salts are constipating and the combination of both salts neutralises each others action and bowel movement may be least affected. 